mobile/gl/gl.go

// Copyright 2014 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build !gldebug

package gl

// TODO(crawshaw): build on more host platforms (makes it easier to gobind).
// TODO(crawshaw): expand to cover OpenGL ES 3.
// TODO(crawshaw): should functions on specific types become methods? E.g.
//                 	func (t Texture) Bind(target Enum)
//                 this seems natural in Go, but moves us slightly
//                 further away from the underlying OpenGL spec.

//#cgo darwin  LDFLAGS: -framework OpenGL
//#cgo linux   LDFLAGS: -lGLESv2
//#include <stdlib.h>
//#include "gl2.h"
import "C"

import "unsafe"

/*
Partially generated from the Khronos OpenGL API specification in XML
format, which is covered by the license:

	Copyright (c) 2013-2014 The Khronos Group Inc.

	Permission is hereby granted, free of charge, to any person obtaining a
	copy of this software and/or associated documentation files (the
	"Materials"), to deal in the Materials without restriction, including
	without limitation the rights to use, copy, modify, merge, publish,
	distribute, sublicense, and/or sell copies of the Materials, and to
	permit persons to whom the Materials are furnished to do so, subject to
	the following conditions:

	The above copyright notice and this permission notice shall be included
	in all copies or substantial portions of the Materials.

	THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
	IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
	CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
	TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
	MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.

*/

// ActiveTexture sets the active texture unit.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glActiveTexture.xhtml
func ActiveTexture(texture Enum) {
	C.glActiveTexture(texture.c())
}

// AttachShader attaches a shader to a program.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glAttachShader.xhtml
func AttachShader(p Program, s Shader) {
	C.glAttachShader(p.c(), s.c())
}

// BindAttribLocation binds a vertex attribute index with a named
// variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindAttribLocation.xhtml
func BindAttribLocation(p Program, a Attrib, name string) {
	str := unsafe.Pointer(C.CString(name))
	defer C.free(str)
	C.glBindAttribLocation(p.c(), a.c(), (*C.GLchar)(str))
}

// BindBuffer binds a buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindBuffer.xhtml
func BindBuffer(target Enum, b Buffer) {
	C.glBindBuffer(target.c(), b.c())
}

// BindFramebuffer binds a framebuffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindFramebuffer.xhtml
func BindFramebuffer(target Enum, fb Framebuffer) {
	C.glBindFramebuffer(target.c(), fb.c())
}

// BindRenderbuffer binds a render buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindRenderbuffer.xhtml
func BindRenderbuffer(target Enum, rb Renderbuffer) {
	C.glBindRenderbuffer(target.c(), rb.c())
}

// BindTexture binds a texture.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindTexture.xhtml
func BindTexture(target Enum, t Texture) {
	C.glBindTexture(target.c(), t.c())
}

// BlendColor sets the blend color.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendColor.xhtml
func BlendColor(red, green, blue, alpha float32) {
	C.glBlendColor(C.GLfloat(red), C.GLfloat(green), C.GLfloat(blue), C.GLfloat(alpha))
}

// BlendEquation sets both RGB and alpha blend equations.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendEquation.xhtml
func BlendEquation(mode Enum) {
	C.glBlendEquation(mode.c())
}

// BlendEquationSeparate sets RGB and alpha blend equations separately.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendEquationSeparate.xhtml
func BlendEquationSeparate(modeRGB, modeAlpha Enum) {
	C.glBlendEquationSeparate(modeRGB.c(), modeAlpha.c())
}

// BlendFunc sets the pixel blending factors.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendFunc.xhtml
func BlendFunc(sfactor, dfactor Enum) {
	C.glBlendFunc(sfactor.c(), dfactor.c())
}

// BlendFunc sets the pixel RGB and alpha blending factors separately.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendFuncSeparate.xhtml
func BlendFuncSeparate(sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha Enum) {
	C.glBlendFuncSeparate(sfactorRGB.c(), dfactorRGB.c(), sfactorAlpha.c(), dfactorAlpha.c())
}

// BufferData creates a new data store for the bound buffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferData.xhtml
func BufferData(target Enum, usage Enum, src []byte) {
	C.glBufferData(target.c(), C.GLsizeiptr(len(src)), unsafe.Pointer(&src[0]), usage.c())
}

// BufferInit creates a new unitialized data store for the bound buffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferData.xhtml
func BufferInit(target Enum, size int, usage Enum) {
	C.glBufferData(target.c(), C.GLsizeiptr(size), nil, usage.c())
}

// BufferSubData sets some of data in the bound buffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferSubData.xhtml
func BufferSubData(target Enum, offset int, data []byte) {
	C.glBufferSubData(target.c(), C.GLintptr(offset), C.GLsizeiptr(len(data)), unsafe.Pointer(&data[0]))
}

// CheckFramebufferStatus reports the completeness status of the
// active framebuffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCheckFramebufferStatus.xhtml
func CheckFramebufferStatus(target Enum) Enum {
	return Enum(C.glCheckFramebufferStatus(target.c()))
}

// Clear clears the window.
//
// The behavior of Clear is influenced by the pixel ownership test,
// the scissor test, dithering, and the buffer writemasks.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glClear.xhtml
func Clear(mask Enum) {
	C.glClear(C.GLbitfield(mask))
}

// ClearColor specifies the RGBA values used to clear color buffers.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearColor.xhtml
func ClearColor(red, green, blue, alpha float32) {
	C.glClearColor(C.GLfloat(red), C.GLfloat(green), C.GLfloat(blue), C.GLfloat(alpha))
}

// ClearDepthf sets the depth value used to clear the depth buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearDepthf.xhtml
func ClearDepthf(d float32) {
	C.glClearDepthf(C.GLfloat(d))
}

// ClearStencil sets the index used to clear the stencil buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearStencil.xhtml
func ClearStencil(s int) {
	C.glClearStencil(C.GLint(s))
}

// ColorMask specifies whether color components in the framebuffer
// can be written.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glColorMask.xhtml
func ColorMask(red, green, blue, alpha bool) {
	C.glColorMask(glBoolean(red), glBoolean(green), glBoolean(blue), glBoolean(alpha))
}

// CompileShader compiles the source code of s.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompileShader.xhtml
func CompileShader(s Shader) {
	C.glCompileShader(s.c())
}

// CompressedTexImage2D writes a compressed 2D texture.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompressedTexImage2D.xhtml
func CompressedTexImage2D(target Enum, level int, internalformat Enum, width, height, border int, data []byte) {
	C.glCompressedTexImage2D(target.c(), C.GLint(level), internalformat.c(), C.GLsizei(width), C.GLsizei(height), C.GLint(border), C.GLsizei(len(data)), unsafe.Pointer(&data[0]))
}

// CompressedTexSubImage2D writes a subregion of a compressed 2D texture.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompressedTexSubImage2D.xhtml
func CompressedTexSubImage2D(target Enum, level, xoffset, yoffset, width, height int, format Enum, data []byte) {
	C.glCompressedTexSubImage2D(target.c(), C.GLint(level), C.GLint(xoffset), C.GLint(yoffset), C.GLsizei(width), C.GLsizei(height), format.c(), C.GLsizei(len(data)), unsafe.Pointer(&data[0]))
}

// CopyTexImage2D writes a 2D texture from the current framebuffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCopyTexImage2D.xhtml
func CopyTexImage2D(target Enum, level int, internalformat Enum, x, y, width, height, border int) {
	C.glCopyTexImage2D(target.c(), C.GLint(level), internalformat.c(), C.GLint(x), C.GLint(y), C.GLsizei(width), C.GLsizei(height), C.GLint(border))
}

// CopyTexSubImage2D writes a 2D texture subregion from the
// current framebuffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCopyTexSubImage2D.xhtml
func CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int) {
	C.glCopyTexSubImage2D(target.c(), C.GLint(level), C.GLint(xoffset), C.GLint(yoffset), C.GLint(x), C.GLint(y), C.GLsizei(width), C.GLsizei(height))
}

// CreateProgram creates a new empty program object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCreateProgram.xhtml
func CreateProgram() Program {
	return Program{Value: uint32(C.glCreateProgram())}
}

// CreateShader creates a new empty shader object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCreateShader.xhtml
func CreateShader(ty Enum) Shader {
	return Shader{Value: uint32(C.glCreateShader(ty.c()))}
}

// CullFace specifies which polygons are candidates for culling.
//
// Valid modes: FRONT, BACK, FRONT_AND_BACK.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glCullFace.xhtml
func CullFace(mode Enum) {
	C.glCullFace(mode.c())
}

// DeleteBuffer deletes the given buffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteBuffers.xhtml
func DeleteBuffer(v Buffer) {
	C.glDeleteBuffers(1, (*C.GLuint)(&v.Value))
}

// DeleteFramebuffer deletes the given framebuffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteFramebuffers.xhtml
func DeleteFramebuffer(v Framebuffer) {
	C.glDeleteFramebuffers(1, (*C.GLuint)(&v.Value))
}

// DeleteProgram deletes the given program object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteProgram.xhtml
func DeleteProgram(p Program) {
	C.glDeleteProgram(p.c())
}

// DeleteRenderbuffer deletes the given render buffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteRenderbuffers.xhtml
func DeleteRenderbuffer(v Renderbuffer) {
	C.glDeleteRenderbuffers(1, (*C.GLuint)(&v.Value))
}

// DeleteShader deletes shader s.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteShader.xhtml
func DeleteShader(s Shader) {
	C.glDeleteShader(s.c())
}

// DeleteTexture deletes the given texture object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteTextures.xhtml
func DeleteTexture(v Texture) {
	C.glDeleteTextures(1, (*C.GLuint)(&v.Value))
}

// DepthFunc sets the function used for depth buffer comparisons.
//
// Valid fn values:
//	NEVER
//	LESS
//	EQUAL
//	LEQUAL
//	GREATER
//	NOTEQUAL
//	GEQUAL
//	ALWAYS
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthFunc.xhtml
func DepthFunc(fn Enum) {
	C.glDepthFunc(fn.c())
}

// DepthMask sets the depth buffer enabled for writing.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthMask.xhtml
func DepthMask(flag bool) {
	C.glDepthMask(glBoolean(flag))
}

// DepthRangef sets the mapping from normalized device coordinates to
// window coordinates.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthRangef.xhtml
func DepthRangef(n, f float32) {
	C.glDepthRangef(C.GLfloat(n), C.GLfloat(f))
}

// DetachShader detaches the shader s from the program p.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDetachShader.xhtml
func DetachShader(p Program, s Shader) {
	C.glDetachShader(p.c(), s.c())
}

// Disable disables various GL capabilities.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDisable.xhtml
func Disable(cap Enum) {
	C.glDisable(cap.c())
}

// http://www.khronos.org/opengles/sdk/docs/man3/html/glDisableVertexAttribArray.xhtml
func DisableVertexAttribArray(index Attrib) {
	C.glDisableVertexAttribArray(index.c())
}

// DrawArrays renders geometric primitives from the bound data.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDrawArrays.xhtml
func DrawArrays(mode Enum, first, count int) {
	C.glDrawArrays(mode.c(), C.GLint(first), C.GLsizei(count))
}

// DrawElements renders primitives from a bound buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glDrawElements.xhtml
func DrawElements(mode, ty Enum, offset, count int) {
	C.glDrawElements(mode.c(), C.GLsizei(count), ty.c(), unsafe.Pointer(uintptr(offset)))
}

// TODO(crawshaw): consider DrawElements8 / DrawElements16 / DrawElements32

// Enable enables various GL capabilities.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glEnable.xhtml
func Enable(cap Enum) {
	C.glEnable(cap.c())
}

// EnableVertexAttribArray enables a vertex attribute array.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glEnableVertexAttribArray.xhtml
func EnableVertexAttribArray(index Attrib) {
	C.glEnableVertexAttribArray(index.c())
}

// Finish blocks until the effects of all previously called GL
// commands are complete.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glFinish.xhtml
func Finish() {
	C.glFinish()
}

// Flush empties all buffers. It does not block.
//
// An OpenGL implementation may buffer network communication,
// the command stream, or data inside the graphics accelerator.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glFlush.xhtml
func Flush() {
	C.glFlush()
}

// FramebufferRenderbuffer attaches rb to the current frame buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glFramebufferRenderbuffer.xhtml
func FramebufferRenderbuffer(target, attachment, rbTarget Enum, rb Renderbuffer) {
	C.glFramebufferRenderbuffer(target.c(), attachment.c(), rbTarget.c(), rb.c())
}

// FramebufferTexture2D attaches the t to the current frame buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glFramebufferTexture2D.xhtml
func FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level int) {
	C.glFramebufferTexture2D(target.c(), attachment.c(), texTarget.c(), t.c(), C.GLint(level))
}

// FrontFace defines which polygons are front-facing.
//
// Valid modes: CW, CCW.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glFrontFace.xhtml
func FrontFace(mode Enum) {
	C.glFrontFace(mode.c())
}

// GenBuffer creates a buffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenBuffers.xhtml
func GenBuffer() Buffer {
	var b Buffer
	C.glGenBuffers(1, (*C.GLuint)(&b.Value))
	return b
}

// GenerateMipmap generates mipmaps for the current texture.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenerateMipmap.xhtml
func GenerateMipmap(target Enum) {
	C.glGenerateMipmap(target.c())
}

// GenFramebuffer creates a framebuffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenFramebuffers.xhtml
func GenFramebuffer() Framebuffer {
	var b Framebuffer
	C.glGenFramebuffers(1, (*C.GLuint)(&b.Value))
	return b
}

// GenRenderbuffer create a renderbuffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenRenderbuffers.xhtml
func GenRenderbuffer() Renderbuffer {
	var b Renderbuffer
	C.glGenRenderbuffers(1, (*C.GLuint)(&b.Value))
	return b
}

// GenTexture creates a texture object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenTextures.xhtml
func GenTexture() Texture {
	var t Texture
	C.glGenTextures(1, (*C.GLuint)(&t.Value))
	return t
}

// GetActiveAttrib returns details about an attribute variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetActiveAttrib.xhtml
func GetActiveAttrib(p Program, a Attrib) (name string, size int, ty Enum) {
	bufSize := GetProgrami(p, ACTIVE_ATTRIBUTE_MAX_LENGTH)
	buf := C.malloc(C.size_t(bufSize))
	defer C.free(buf)

	var cSize C.GLint
	var cType C.GLenum
	C.glGetActiveAttrib(p.c(), a.c(), C.GLsizei(bufSize), nil, &cSize, &cType, (*C.GLchar)(buf))
	return C.GoString((*C.char)(buf)), int(cSize), Enum(cType)
}

// GetActiveUniform returns details about an active uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetActiveUniform.xhtml
func GetActiveUniform(p Program, u Uniform) (name string, size int, ty Enum) {
	bufSize := GetProgrami(p, ACTIVE_UNIFORM_MAX_LENGTH)
	buf := C.malloc(C.size_t(bufSize))
	defer C.free(buf)

	var cSize C.GLint
	var cType C.GLenum

	C.glGetActiveUniform(p.c(), C.GLuint(u.Value), C.GLsizei(bufSize), nil, &cSize, &cType, (*C.GLchar)(buf))
	return C.GoString((*C.char)(buf)), int(cSize), Enum(cType)
}

// GetAttachedShaders returns the shader objects attached to program p.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetAttachedShaders.xhtml
func GetAttachedShaders(p Program) []Shader {
	shadersLen := GetProgrami(p, ATTACHED_SHADERS)
	var n C.GLsizei
	buf := make([]C.GLuint, shadersLen)
	C.glGetAttachedShaders(p.c(), C.GLsizei(shadersLen), &n, &buf[0])
	buf = buf[:int(n)]
	shaders := make([]Shader, len(buf))
	for i, s := range buf {
		shaders[i] = Shader{Value: uint32(s)}
	}
	return shaders
}

// GetAttribLocation finds a program attribute variable by name.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetAttribLocation.xhtml
func GetAttribLocation(p Program, name string) Attrib {
	str := unsafe.Pointer(C.CString(name))
	defer C.free(str)
	return Attrib{Value: uint(C.glGetAttribLocation(p.c(), (*C.GLchar)(str)))}
}

// GetBooleanv returns the boolean values of parameter pname.
//
// Many boolean parameters can be queried more easily using IsEnabled.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
func GetBooleanv(dst []bool, pname Enum) {
	buf := make([]C.GLboolean, len(dst))
	C.glGetBooleanv(pname.c(), &buf[0])
	for i, v := range buf {
		dst[i] = v != 0
	}
}

// GetFloatv returns the float values of parameter pname.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
func GetFloatv(dst []float32, pname Enum) {
	C.glGetFloatv(pname.c(), (*C.GLfloat)(&dst[0]))
}

// GetIntegerv returns the int values of parameter pname.
//
// Single values may be queried more easily using GetInteger.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
func GetIntegerv(pname Enum, data []int32) {
	buf := make([]C.GLint, len(data))
	C.glGetIntegerv(pname.c(), &buf[0])
	for i, v := range buf {
		data[i] = int32(v)
	}
}

// GetInteger returns the int value of parameter pname.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
func GetInteger(pname Enum) int {
	var v C.GLint
	C.glGetIntegerv(pname.c(), &v)
	return int(v)
}

// GetBufferParameteri returns a parameter for the active buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetBufferParameteriv.xhtml
func GetBufferParameteri(target, pname Enum) int {
	var params C.GLint
	C.glGetBufferParameteriv(target.c(), pname.c(), &params)
	return int(params)
}

// GetError returns the next error.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetError.xhtml
func GetError() Enum {
	return Enum(C.glGetError())
}

// GetFramebufferAttachmentParameteri returns attachment parameters
// for the active framebuffer object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetFramebufferAttachmentParameteriv.xhtml
func GetFramebufferAttachmentParameteri(target, attachment, pname Enum) int {
	var params C.GLint
	C.glGetFramebufferAttachmentParameteriv(target.c(), attachment.c(), pname.c(), &params)
	return int(params)
}

// GetProgrami returns a parameter value for a program.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetProgramiv.xhtml
func GetProgrami(p Program, pname Enum) int {
	var params C.GLint
	C.glGetProgramiv(p.c(), pname.c(), &params)
	return int(params)
}

// GetProgramInfoLog returns the information log for a program.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetProgramInfoLog.xhtml
func GetProgramInfoLog(p Program) string {
	infoLen := GetProgrami(p, INFO_LOG_LENGTH)
	buf := C.malloc(C.size_t(infoLen))
	C.free(buf)
	C.glGetProgramInfoLog(p.c(), C.GLsizei(infoLen), nil, (*C.GLchar)(buf))
	return C.GoString((*C.char)(buf))
}

// GetShaderi returns a parameter value for a render buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetRenderbufferParameteriv.xhtml
func GetRenderbufferParameteri(target, pname Enum) int {
	var params C.GLint
	C.glGetRenderbufferParameteriv(target.c(), pname.c(), &params)
	return int(params)
}

// GetRenderbufferParameteri returns a parameter value for a shader.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderiv.xhtml
func GetShaderi(s Shader, pname Enum) int {
	var params C.GLint
	C.glGetShaderiv(s.c(), pname.c(), &params)
	return int(params)
}

// GetShaderInfoLog returns the information log for a shader.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderInfoLog.xhtml
func GetShaderInfoLog(s Shader) string {
	infoLen := GetShaderi(s, INFO_LOG_LENGTH)
	buf := C.malloc(C.size_t(infoLen))
	defer C.free(buf)
	C.glGetShaderInfoLog(s.c(), C.GLsizei(infoLen), nil, (*C.GLchar)(buf))
	return C.GoString((*C.char)(buf))
}

// GetShaderPrecisionFormat returns range and precision limits for
// shader types.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderPrecisionFormat.xhtml
func GetShaderPrecisionFormat(shadertype, precisiontype Enum) (rangeLow, rangeHigh, precision int) {
	const glintSize = 4
	var cRange [2]C.GLint
	var cPrecision C.GLint

	C.glGetShaderPrecisionFormat(shadertype.c(), precisiontype.c(), &cRange[0], &cPrecision)
	return int(cRange[0]), int(cRange[1]), int(cPrecision)
}

// GetShaderSource returns source code of shader s.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderSource.xhtml
func GetShaderSource(s Shader) string {
	sourceLen := GetShaderi(s, SHADER_SOURCE_LENGTH)
	if sourceLen == 0 {
		return ""
	}
	buf := C.malloc(C.size_t(sourceLen))
	defer C.free(buf)
	C.glGetShaderSource(s.c(), C.GLsizei(sourceLen), nil, (*C.GLchar)(buf))
	return C.GoString((*C.char)(buf))
}

// GetString reports current GL state.
//
// Valid name values:
//	EXTENSIONS
//	RENDERER
//	SHADING_LANGUAGE_VERSION
//	VENDOR
//	VERSION
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetString.xhtml
func GetString(name Enum) string {
	// Bounce through unsafe.Pointer, because on some platforms
	// GetString returns an *unsigned char which doesn't convert.
	return C.GoString((*C.char)((unsafe.Pointer)(C.glGetString(name.c()))))
}

// GetTexParameterfv returns the float values of a texture parameter.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetTexParameter.xhtml
func GetTexParameterfv(dst []float32, target, pname Enum) {
	C.glGetTexParameterfv(target.c(), pname.c(), (*C.GLfloat)(&dst[0]))
}

// GetTexParameteriv returns the int values of a texture parameter.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetTexParameter.xhtml
func GetTexParameteriv(dst []int32, target, pname Enum) {
	C.glGetTexParameteriv(target.c(), pname.c(), (*C.GLint)(&dst[0]))
}

// GetUniformfv returns the float values of a uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniform.xhtml
func GetUniformfv(dst []float32, src Uniform, p Program) {
	C.glGetUniformfv(p.c(), src.c(), (*C.GLfloat)(&dst[0]))
}

// GetUniformiv returns the float values of a uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniform.xhtml
func GetUniformiv(dst []int32, src Uniform, p Program) {
	C.glGetUniformiv(p.c(), src.c(), (*C.GLint)(&dst[0]))
}

// GetUniformLocation returns the location of uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniformLocation.xhtml
func GetUniformLocation(p Program, name string) Uniform {
	str := C.CString(name)
	defer C.free((unsafe.Pointer)(str))
	return Uniform{Value: int32(C.glGetUniformLocation(p.c(), (*C.GLchar)(str)))}
}

// GetVertexAttribf reads the float value of a vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
func GetVertexAttribf(src Attrib, pname Enum) float32 {
	var params C.GLfloat
	C.glGetVertexAttribfv(src.c(), pname.c(), &params)
	return float32(params)
}

// GetVertexAttribfv reads float values of a vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
func GetVertexAttribfv(dst []float32, src Attrib, pname Enum) {
	C.glGetVertexAttribfv(src.c(), pname.c(), (*C.GLfloat)(&dst[0]))
}

// GetVertexAttribi reads the int value of a vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
func GetVertexAttribi(src Attrib, pname Enum) int32 {
	var params C.GLint
	C.glGetVertexAttribiv(src.c(), pname.c(), &params)
	return int32(params)
}

// GetVertexAttribiv reads int values of a vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
func GetVertexAttribiv(dst []int32, src Attrib, pname Enum) {
	C.glGetVertexAttribiv(src.c(), pname.c(), (*C.GLint)(&dst[0]))
}

// TODO(crawshaw): glGetVertexAttribPointerv

// Hint sets implementation-specific modes.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glHint.xhtml
func Hint(target, mode Enum) {
	C.glHint(target.c(), mode.c())
}

// IsBuffer reports if b is a valid buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsBuffer.xhtml
func IsBuffer(b Buffer) bool {
	return C.glIsBuffer(b.c()) != 0
}

// IsEnabled reports if cap is an enabled capability.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsEnabled.xhtml
func IsEnabled(cap Enum) bool {
	return C.glIsEnabled(cap.c()) != 0
}

// IsFramebuffer reports if fb is a valid frame buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsFramebuffer.xhtml
func IsFramebuffer(fb Framebuffer) bool {
	return C.glIsFramebuffer(fb.c()) != 0
}

// IsProgram reports if p is a valid program object.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsProgram.xhtml
func IsProgram(p Program) bool {
	return C.glIsProgram(p.c()) != 0
}

// IsRenderbuffer reports if rb is a valid render buffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsRenderbuffer.xhtml
func IsRenderbuffer(rb Renderbuffer) bool {
	return C.glIsRenderbuffer(rb.c()) != 0
}

// IsShader reports if s is valid shader.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsShader.xhtml
func IsShader(s Shader) bool {
	return C.glIsShader(s.c()) != 0
}

// IsTexture reports if t is a valid texture.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsTexture.xhtml
func IsTexture(t Texture) bool {
	return C.glIsTexture(t.c()) != 0
}

// LineWidth specifies the width of lines.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glLineWidth.xhtml
func LineWidth(width float32) {
	C.glLineWidth(C.GLfloat(width))
}

// LinkProgram links the specified program.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glLinkProgram.xhtml
func LinkProgram(p Program) {
	C.glLinkProgram(p.c())
}

// PixelStorei sets pixel storage parameters.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glPixelStorei.xhtml
func PixelStorei(pname Enum, param int32) {
	C.glPixelStorei(pname.c(), C.GLint(param))
}

// PolygonOffset sets the scaling factors for depth offsets.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glPolygonOffset.xhtml
func PolygonOffset(factor, units float32) {
	C.glPolygonOffset(C.GLfloat(factor), C.GLfloat(units))
}

// ReadPixels returns pixel data from a buffer.
//
// In GLES 3, the source buffer is controlled with ReadBuffer.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glReadPixels.xhtml
func ReadPixels(dst []byte, x, y, width, height int, format, ty Enum) {
	// TODO(crawshaw): support PIXEL_PACK_BUFFER in GLES3, uses offset.
	C.glReadPixels(C.GLint(x), C.GLint(y), C.GLsizei(width), C.GLsizei(height), format.c(), ty.c(), unsafe.Pointer(&dst[0]))
}

// ReleaseShaderCompiler frees resources allocated by the shader compiler.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glReleaseShaderCompiler.xhtml
func ReleaseShaderCompiler() {
	C.glReleaseShaderCompiler()
}

// RenderbufferStorage establishes the data storage, format, and
// dimensions of a renderbuffer object's image.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glRenderbufferStorage.xhtml
func RenderbufferStorage(target, internalFormat Enum, width, height int) {
	C.glRenderbufferStorage(target.c(), internalFormat.c(), C.GLsizei(width), C.GLsizei(height))
}

// SampleCoverage sets multisample coverage parameters.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glSampleCoverage.xhtml
func SampleCoverage(value float32, invert bool) {
	C.glSampleCoverage(C.GLfloat(value), glBoolean(invert))
}

func glBoolean(b bool) C.GLboolean {
	if b {
		return 0
	}
	return 1
}

// Scissor defines the scissor box rectangle, in window coordinates.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glScissor.xhtml
func Scissor(x, y, width, height int32) {
	C.glScissor(C.GLint(x), C.GLint(y), C.GLsizei(width), C.GLsizei(height))
}

// TODO(crawshaw): ShaderBinary

// ShaderSource sets the source code of s to the given source code.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glShaderSource.xhtml
func ShaderSource(s Shader, src string) {
	str := (*C.GLchar)(C.CString(src))
	defer C.free(unsafe.Pointer(str))
	C.glShaderSource(s.c(), 1, &str, nil)
}

//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilFunc.xhtml
func StencilFunc(fn Enum, ref int, mask uint32) {
	C.glStencilFunc(fn.c(), C.GLint(ref), C.GLuint(mask))
}

//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilFuncSeparate.xhtml
func StencilFuncSeparate(face, fn Enum, ref int, mask uint32) {
	C.glStencilFuncSeparate(face.c(), fn.c(), C.GLint(ref), C.GLuint(mask))
}

// StencilMask controls the writing of bits in the stencil planes.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilMask.xhtml
func StencilMask(mask uint32) {
	C.glStencilMask(C.GLuint(mask))
}

// StencilMaskSeparate controls the writing of bits in the stencil planes.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilMaskSeparate.xhtml
func StencilMaskSeparate(face Enum, mask uint32) {
	C.glStencilMaskSeparate(face.c(), C.GLuint(mask))
}

// StencilOp sets front and back stencil test actions.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilOp.xhtml
func StencilOp(fail, zfail, zpass Enum) {
	C.glStencilOp(fail.c(), zfail.c(), zpass.c())
}

// StencilOpSeparate sets front or back stencil tests.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilOpSeparate.xhtml
func StencilOpSeparate(face, sfail, dpfail, dppass Enum) {
	C.glStencilOpSeparate(face.c(), sfail.c(), dpfail.c(), dppass.c())
}

// TexImage2D writes a 2D texture image.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexImage2D.xhtml
func TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum, data []byte) {
	// TODO(crawshaw): GLES3 offset for PIXEL_UNPACK_BUFFER and PIXEL_PACK_BUFFER.
	p := unsafe.Pointer(nil)
	if len(data) > 0 {
		p = unsafe.Pointer(&data[0])
	}
	C.glTexImage2D(target.c(), C.GLint(level), C.GLint(format), C.GLsizei(width), C.GLsizei(height), 0, format.c(), ty.c(), p)
}

// TexSubImage2D writes a subregion of a 2D texture image.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexSubImage2D.xhtml
func TexSubImage2D(target Enum, level int, x, y, width, height int, format, ty Enum, data []byte) {
	// TODO(crawshaw): GLES3 offset for PIXEL_UNPACK_BUFFER and PIXEL_PACK_BUFFER.
	C.glTexSubImage2D(target.c(), C.GLint(level), C.GLint(x), C.GLint(y), C.GLsizei(width), C.GLsizei(height), format.c(), ty.c(), unsafe.Pointer(&data[0]))
}

// TexParameterf sets a float texture parameter.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
func TexParameterf(target, pname Enum, param float32) {
	C.glTexParameterf(target.c(), pname.c(), C.GLfloat(param))
}

// TexParameterfv sets a float texture parameter array.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
func TexParameterfv(target, pname Enum, params []float32) {
	C.glTexParameterfv(target.c(), pname.c(), (*C.GLfloat)(&params[0]))
}

// TexParameteri sets an integer texture parameter.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
func TexParameteri(target, pname Enum, param int) {
	C.glTexParameteri(target.c(), pname.c(), C.GLint(param))
}

// TexParameteriv sets an integer texture parameter array.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
func TexParameteriv(target, pname Enum, params []int32) {
	C.glTexParameteriv(target.c(), pname.c(), (*C.GLint)(&params[0]))
}

// Uniform1f writes a float uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform1f(dst Uniform, v float32) {
	C.glUniform1f(dst.c(), C.GLfloat(v))
}

// Uniform1fv writes a [len(src)]float uniform array.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform1fv(dst Uniform, src []float32) {
	C.glUniform1fv(dst.c(), C.GLsizei(len(src)), (*C.GLfloat)(&src[0]))
}

// Uniform1i writes an int uniform variable.
//
// Uniform1i and Uniform1iv are the only two functions that may be used
// to load uniform variables defined as sampler types. Loading samplers
// with any other function will result in a INVALID_OPERATION error.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform1i(dst Uniform, v int) {
	C.glUniform1i(dst.c(), C.GLint(v))
}

// Uniform1iv writes a int uniform array of len(src) elements.
//
// Uniform1i and Uniform1iv are the only two functions that may be used
// to load uniform variables defined as sampler types. Loading samplers
// with any other function will result in a INVALID_OPERATION error.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform1iv(dst Uniform, src []int32) {
	C.glUniform1iv(dst.c(), C.GLsizei(len(src)), (*C.GLint)(&src[0]))
}

// Uniform2f writes a vec2 uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform2f(dst Uniform, v0, v1 float32) {
	C.glUniform2f(dst.c(), C.GLfloat(v0), C.GLfloat(v1))
}

// Uniform2fv writes a vec2 uniform array of len(src)/2 elements.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform2fv(dst Uniform, src []float32) {
	C.glUniform2fv(dst.c(), C.GLsizei(len(src)/2), (*C.GLfloat)(&src[0]))
}

// Uniform2i writes an ivec2 uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform2i(location, v0, v1 int) {
	C.glUniform2i(C.GLint(location), C.GLint(v0), C.GLint(v1))
}

// Uniform2iv writes an ivec2 uniform array of len(src)/2 elements.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform2iv(dst Uniform, src []int32) {
	C.glUniform2iv(dst.c(), C.GLsizei(len(src)/2), (*C.GLint)(&src[0]))
}

// Uniform3f writes a vec3 uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform3f(dst Uniform, v0, v1, v2 float32) {
	C.glUniform3f(dst.c(), C.GLfloat(v0), C.GLfloat(v1), C.GLfloat(v2))
}

// Uniform3fv writes a vec3 uniform array of len(src)/3 elements.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform3fv(dst Uniform, src []float32) {
	C.glUniform3fv(dst.c(), C.GLsizei(len(src)/3), (*C.GLfloat)(&src[0]))
}

// Uniform3i writes an ivec3 uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform3i(location, v0, v1, v2 int32) {
	C.glUniform3i(C.GLint(location), C.GLint(v0), C.GLint(v1), C.GLint(v2))
}

// Uniform3iv writes an ivec3 uniform array of len(src)/3 elements.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform3iv(dst Uniform, src []int32) {
	C.glUniform3iv(dst.c(), C.GLsizei(len(src)/3), (*C.GLint)(&src[0]))
}

// Uniform4f writes a vec4 uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform4f(dst Uniform, v0, v1, v2, v3 float32) {
	C.glUniform4f(dst.c(), C.GLfloat(v0), C.GLfloat(v1), C.GLfloat(v2), C.GLfloat(v3))
}

// Uniform4fv writes a vec4 uniform array of len(src)/4 elements.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform4fv(dst Uniform, src []float32) {
	C.glUniform4fv(dst.c(), C.GLsizei(len(src)/4), (*C.GLfloat)(&src[0]))
}

// Uniform4i writes an ivec4 uniform variable.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform4i(dst Uniform, v0, v1, v2, v3 int32) {
	C.glUniform4i(dst.c(), C.GLint(v0), C.GLint(v1), C.GLint(v2), C.GLint(v3))
}

// Uniform4i writes an ivec4 uniform array of len(src)/4 elements.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func Uniform4iv(dst Uniform, src []int32) {
	C.glUniform4iv(dst.c(), C.GLsizei(len(src)/4), (*C.GLint)(&src[0]))
}

// UniformMatrix2fv writes 2x2 matricies. Each matrix uses four
// float32 values, so the number of matricies written is len(src)/4.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func UniformMatrix2fv(dst Uniform, src []float32) {
	/// OpenGL ES 2 does not support transpose.
	C.glUniformMatrix2fv(dst.c(), C.GLsizei(len(src)/4), 0, (*C.GLfloat)(&src[0]))
}

// UniformMatrix3fv writes 3x3 matricies. Each matrix uses nine
// float32 values, so the number of matricies written is len(src)/9.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func UniformMatrix3fv(dst Uniform, src []float32) {
	C.glUniformMatrix3fv(dst.c(), C.GLsizei(len(src)/9), 0, (*C.GLfloat)(&src[0]))
}

// UniformMatrix4fv writes 4x4 matricies. Each matrix uses 16
// float32 values, so the number of matricies written is len(src)/16.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
func UniformMatrix4fv(dst Uniform, src []float32) {
	C.glUniformMatrix4fv(dst.c(), C.GLsizei(len(src)/16), 0, (*C.GLfloat)(&src[0]))
}

// UseProgram sets the active program.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glUseProgram.xhtml
func UseProgram(p Program) {
	C.glUseProgram(p.c())
}

// ValidateProgram checks to see whether the executables contained in
// program can execute given the current OpenGL state.
//
// Typically only used for debugging.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glValidateProgram.xhtml
func ValidateProgram(p Program) {
	C.glValidateProgram(p.c())
}

// VertexAttrib1f writes a float vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
func VertexAttrib1f(dst Attrib, x float32) {
	C.glVertexAttrib1f(dst.c(), C.GLfloat(x))
}

// VertexAttrib1fv writes a float vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
func VertexAttrib1fv(dst Attrib, src []float32) {
	C.glVertexAttrib1fv(dst.c(), (*C.GLfloat)(&src[0]))
}

// VertexAttrib2f writes a vec2 vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
func VertexAttrib2f(dst Attrib, x, y float32) {
	C.glVertexAttrib2f(dst.c(), C.GLfloat(x), C.GLfloat(y))
}

// VertexAttrib2fv writes a vec2 vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
func VertexAttrib2fv(dst Attrib, src []float32) {
	C.glVertexAttrib2fv(dst.c(), (*C.GLfloat)(&src[0]))
}

// VertexAttrib3f writes a vec3 vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
func VertexAttrib3f(dst Attrib, x, y, z float32) {
	C.glVertexAttrib3f(dst.c(), C.GLfloat(x), C.GLfloat(y), C.GLfloat(z))
}

// VertexAttrib3fv writes a vec3 vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
func VertexAttrib3fv(dst Attrib, src []float32) {
	C.glVertexAttrib3fv(dst.c(), (*C.GLfloat)(&src[0]))
}

// VertexAttrib4f writes a vec4 vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
func VertexAttrib4f(dst Attrib, x, y, z, w float32) {
	C.glVertexAttrib4f(dst.c(), C.GLfloat(x), C.GLfloat(y), C.GLfloat(z), C.GLfloat(w))
}

// VertexAttrib4fv writes a vec4 vertex attribute.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
func VertexAttrib4fv(dst Attrib, src []float32) {
	C.glVertexAttrib4fv(dst.c(), (*C.GLfloat)(&src[0]))
}

// VertexAttribPointer uses a bound bufer to define vertex attribute data.
//
// Direct use of VertexAttribPointer to load data into OpenGL is not
// supported via the Go bindings. Instead, use BindBuffer with an
// ARRAY_BUFFER and then fill it using BufferData.
//
// The size argument specifies the number of components per attribute,
// between 1-4. The stride argument specifies the byte offset between
// consecutive vertex attributes.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttribPointer.xhtml
func VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride, offset int) {
	n := glBoolean(normalized)
	s := C.GLsizei(stride)
	C.glVertexAttribPointer(dst.c(), C.GLint(size), ty.c(), n, s, unsafe.Pointer(uintptr(offset)))
}

// Viewport sets the viewport, an affine transformation that
// normalizes device coordinates to window coordinates.
//
// http://www.khronos.org/opengles/sdk/docs/man3/html/glViewport.xhtml
func Viewport(x, y, width, height int) {
	C.glViewport(C.GLint(x), C.GLint(y), C.GLsizei(width), C.GLsizei(height))
}