ebiten/internal/graphicsdriver/opengl/gl/default_purego.go
2024-04-29 21:25:15 +09:00

570 lines
21 KiB
Go

// Copyright 2022 The Ebitengine Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:build (darwin || freebsd || linux || netbsd || openbsd || windows) && !nintendosdk && !playstation5
package gl
import (
"runtime"
"unsafe"
"github.com/ebitengine/purego"
)
type defaultContext struct {
gpActiveTexture uintptr
gpAttachShader uintptr
gpBindAttribLocation uintptr
gpBindBuffer uintptr
gpBindFramebuffer uintptr
gpBindRenderbuffer uintptr
gpBindTexture uintptr
gpBindVertexArray uintptr
gpBlendEquationSeparate uintptr
gpBlendFuncSeparate uintptr
gpBufferData uintptr
gpBufferSubData uintptr
gpCheckFramebufferStatus uintptr
gpClear uintptr
gpColorMask uintptr
gpCompileShader uintptr
gpCreateProgram uintptr
gpCreateShader uintptr
gpDeleteBuffers uintptr
gpDeleteFramebuffers uintptr
gpDeleteProgram uintptr
gpDeleteRenderbuffers uintptr
gpDeleteShader uintptr
gpDeleteTextures uintptr
gpDeleteVertexArrays uintptr
gpDisable uintptr
gpDisableVertexAttribArray uintptr
gpDrawElements uintptr
gpEnable uintptr
gpEnableVertexAttribArray uintptr
gpFlush uintptr
gpFramebufferRenderbuffer uintptr
gpFramebufferTexture2D uintptr
gpGenBuffers uintptr
gpGenFramebuffers uintptr
gpGenRenderbuffers uintptr
gpGenTextures uintptr
gpGenVertexArrays uintptr
gpGetError uintptr
gpGetIntegerv uintptr
gpGetProgramInfoLog uintptr
gpGetProgramiv uintptr
gpGetShaderInfoLog uintptr
gpGetShaderiv uintptr
gpGetUniformLocation uintptr
gpIsFramebuffer uintptr
gpIsProgram uintptr
gpIsRenderbuffer uintptr
gpLinkProgram uintptr
gpPixelStorei uintptr
gpReadPixels uintptr
gpRenderbufferStorage uintptr
gpScissor uintptr
gpShaderSource uintptr
gpStencilFunc uintptr
gpStencilOpSeparate uintptr
gpTexImage2D uintptr
gpTexParameteri uintptr
gpTexSubImage2D uintptr
gpUniform1fv uintptr
gpUniform1i uintptr
gpUniform1iv uintptr
gpUniform2fv uintptr
gpUniform2iv uintptr
gpUniform3fv uintptr
gpUniform3iv uintptr
gpUniform4fv uintptr
gpUniform4iv uintptr
gpUniformMatrix2fv uintptr
gpUniformMatrix3fv uintptr
gpUniformMatrix4fv uintptr
gpUseProgram uintptr
gpVertexAttribPointer uintptr
gpViewport uintptr
isES bool
}
func NewDefaultContext() (Context, error) {
ctx := &defaultContext{}
if err := ctx.init(); err != nil {
return nil, err
}
return ctx, nil
}
func boolToInt(b bool) int {
if b {
return 1
}
return 0
}
func (c *defaultContext) IsES() bool {
return c.isES
}
func (c *defaultContext) ActiveTexture(texture uint32) {
purego.SyscallN(c.gpActiveTexture, uintptr(texture))
}
func (c *defaultContext) AttachShader(program uint32, shader uint32) {
purego.SyscallN(c.gpAttachShader, uintptr(program), uintptr(shader))
}
func (c *defaultContext) BindAttribLocation(program uint32, index uint32, name string) {
cname, free := cStr(name)
defer free()
purego.SyscallN(c.gpBindAttribLocation, uintptr(program), uintptr(index), uintptr(unsafe.Pointer(cname)))
}
func (c *defaultContext) BindBuffer(target uint32, buffer uint32) {
purego.SyscallN(c.gpBindBuffer, uintptr(target), uintptr(buffer))
}
func (c *defaultContext) BindFramebuffer(target uint32, framebuffer uint32) {
purego.SyscallN(c.gpBindFramebuffer, uintptr(target), uintptr(framebuffer))
}
func (c *defaultContext) BindRenderbuffer(target uint32, renderbuffer uint32) {
purego.SyscallN(c.gpBindRenderbuffer, uintptr(target), uintptr(renderbuffer))
}
func (c *defaultContext) BindTexture(target uint32, texture uint32) {
purego.SyscallN(c.gpBindTexture, uintptr(target), uintptr(texture))
}
func (c *defaultContext) BindVertexArray(array uint32) {
purego.SyscallN(c.gpBindVertexArray, uintptr(array))
}
func (c *defaultContext) BlendEquationSeparate(modeRGB uint32, modeAlpha uint32) {
purego.SyscallN(c.gpBlendEquationSeparate, uintptr(modeRGB), uintptr(modeAlpha))
}
func (c *defaultContext) BlendFuncSeparate(srcRGB uint32, dstRGB uint32, srcAlpha uint32, dstAlpha uint32) {
purego.SyscallN(c.gpBlendFuncSeparate, uintptr(srcRGB), uintptr(dstRGB), uintptr(srcAlpha), uintptr(dstAlpha))
}
func (c *defaultContext) BufferInit(target uint32, size int, usage uint32) {
purego.SyscallN(c.gpBufferData, uintptr(target), uintptr(size), 0, uintptr(usage))
}
func (c *defaultContext) BufferSubData(target uint32, offset int, data []byte) {
purego.SyscallN(c.gpBufferSubData, uintptr(target), uintptr(offset), uintptr(len(data)), uintptr(unsafe.Pointer(&data[0])))
runtime.KeepAlive(data)
}
func (c *defaultContext) CheckFramebufferStatus(target uint32) uint32 {
ret, _, _ := purego.SyscallN(c.gpCheckFramebufferStatus, uintptr(target))
return uint32(ret)
}
func (c *defaultContext) Clear(mask uint32) {
purego.SyscallN(c.gpClear, uintptr(mask))
}
func (c *defaultContext) ColorMask(red bool, green bool, blue bool, alpha bool) {
purego.SyscallN(c.gpColorMask, uintptr(boolToInt(red)), uintptr(boolToInt(green)), uintptr(boolToInt(blue)), uintptr(boolToInt(alpha)))
}
func (c *defaultContext) CompileShader(shader uint32) {
purego.SyscallN(c.gpCompileShader, uintptr(shader))
}
func (c *defaultContext) CreateBuffer() uint32 {
var buffer uint32
purego.SyscallN(c.gpGenBuffers, 1, uintptr(unsafe.Pointer(&buffer)))
return buffer
}
func (c *defaultContext) CreateFramebuffer() uint32 {
var framebuffer uint32
purego.SyscallN(c.gpGenFramebuffers, 1, uintptr(unsafe.Pointer(&framebuffer)))
return framebuffer
}
func (c *defaultContext) CreateProgram() uint32 {
ret, _, _ := purego.SyscallN(c.gpCreateProgram)
return uint32(ret)
}
func (c *defaultContext) CreateRenderbuffer() uint32 {
var renderbuffer uint32
purego.SyscallN(c.gpGenRenderbuffers, 1, uintptr(unsafe.Pointer(&renderbuffer)))
return renderbuffer
}
func (c *defaultContext) CreateShader(xtype uint32) uint32 {
ret, _, _ := purego.SyscallN(c.gpCreateShader, uintptr(xtype))
return uint32(ret)
}
func (c *defaultContext) CreateTexture() uint32 {
var texture uint32
purego.SyscallN(c.gpGenTextures, 1, uintptr(unsafe.Pointer(&texture)))
return texture
}
func (c *defaultContext) CreateVertexArray() uint32 {
var array uint32
purego.SyscallN(c.gpGenVertexArrays, 1, uintptr(unsafe.Pointer(&array)))
return array
}
func (c *defaultContext) DeleteBuffer(buffer uint32) {
purego.SyscallN(c.gpDeleteBuffers, 1, uintptr(unsafe.Pointer(&buffer)))
}
func (c *defaultContext) DeleteFramebuffer(framebuffer uint32) {
purego.SyscallN(c.gpDeleteFramebuffers, 1, uintptr(unsafe.Pointer(&framebuffer)))
}
func (c *defaultContext) DeleteProgram(program uint32) {
purego.SyscallN(c.gpDeleteProgram, uintptr(program))
}
func (c *defaultContext) DeleteRenderbuffer(renderbuffer uint32) {
purego.SyscallN(c.gpDeleteRenderbuffers, 1, uintptr(unsafe.Pointer(&renderbuffer)))
}
func (c *defaultContext) DeleteShader(shader uint32) {
purego.SyscallN(c.gpDeleteShader, uintptr(shader))
}
func (c *defaultContext) DeleteTexture(texture uint32) {
purego.SyscallN(c.gpDeleteTextures, 1, uintptr(unsafe.Pointer(&texture)))
}
func (c *defaultContext) DeleteVertexArray(array uint32) {
purego.SyscallN(c.gpDeleteVertexArrays, 1, uintptr(unsafe.Pointer(&array)))
}
func (c *defaultContext) Disable(cap uint32) {
purego.SyscallN(c.gpDisable, uintptr(cap))
}
func (c *defaultContext) DisableVertexAttribArray(index uint32) {
purego.SyscallN(c.gpDisableVertexAttribArray, uintptr(index))
}
func (c *defaultContext) DrawElements(mode uint32, count int32, xtype uint32, offset int) {
purego.SyscallN(c.gpDrawElements, uintptr(mode), uintptr(count), uintptr(xtype), uintptr(offset))
}
func (c *defaultContext) Enable(cap uint32) {
purego.SyscallN(c.gpEnable, uintptr(cap))
}
func (c *defaultContext) EnableVertexAttribArray(index uint32) {
purego.SyscallN(c.gpEnableVertexAttribArray, uintptr(index))
}
func (c *defaultContext) Flush() {
purego.SyscallN(c.gpFlush)
}
func (c *defaultContext) FramebufferRenderbuffer(target uint32, attachment uint32, renderbuffertarget uint32, renderbuffer uint32) {
purego.SyscallN(c.gpFramebufferRenderbuffer, uintptr(target), uintptr(attachment), uintptr(renderbuffertarget), uintptr(renderbuffer))
}
func (c *defaultContext) FramebufferTexture2D(target uint32, attachment uint32, textarget uint32, texture uint32, level int32) {
purego.SyscallN(c.gpFramebufferTexture2D, uintptr(target), uintptr(attachment), uintptr(textarget), uintptr(texture), uintptr(level))
}
func (c *defaultContext) GetError() uint32 {
ret, _, _ := purego.SyscallN(c.gpGetError)
return uint32(ret)
}
func (c *defaultContext) GetInteger(pname uint32) int {
var dst int32
purego.SyscallN(c.gpGetIntegerv, uintptr(pname), uintptr(unsafe.Pointer(&dst)))
return int(dst)
}
func (c *defaultContext) GetProgramInfoLog(program uint32) string {
bufSize := c.GetProgrami(program, INFO_LOG_LENGTH)
infoLog := make([]byte, bufSize)
purego.SyscallN(c.gpGetProgramInfoLog, uintptr(program), uintptr(bufSize), 0, uintptr(unsafe.Pointer(&infoLog[0])))
return string(infoLog)
}
func (c *defaultContext) GetProgrami(program uint32, pname uint32) int {
var dst int32
purego.SyscallN(c.gpGetProgramiv, uintptr(program), uintptr(pname), uintptr(unsafe.Pointer(&dst)))
return int(dst)
}
func (c *defaultContext) GetShaderInfoLog(shader uint32) string {
bufSize := c.GetShaderi(shader, INFO_LOG_LENGTH)
infoLog := make([]byte, bufSize)
purego.SyscallN(c.gpGetShaderInfoLog, uintptr(shader), uintptr(bufSize), 0, uintptr(unsafe.Pointer(&infoLog[0])))
return string(infoLog)
}
func (c *defaultContext) GetShaderi(shader uint32, pname uint32) int {
var dst int32
purego.SyscallN(c.gpGetShaderiv, uintptr(shader), uintptr(pname), uintptr(unsafe.Pointer(&dst)))
return int(dst)
}
func (c *defaultContext) GetUniformLocation(program uint32, name string) int32 {
cname, free := cStr(name)
defer free()
ret, _, _ := purego.SyscallN(c.gpGetUniformLocation, uintptr(program), uintptr(unsafe.Pointer(cname)))
return int32(ret)
}
func (c *defaultContext) IsFramebuffer(framebuffer uint32) bool {
ret, _, _ := purego.SyscallN(c.gpIsFramebuffer, uintptr(framebuffer))
return byte(ret) != 0
}
func (c *defaultContext) IsProgram(program uint32) bool {
ret, _, _ := purego.SyscallN(c.gpIsProgram, uintptr(program))
return byte(ret) != 0
}
func (c *defaultContext) IsRenderbuffer(renderbuffer uint32) bool {
ret, _, _ := purego.SyscallN(c.gpIsRenderbuffer, uintptr(renderbuffer))
return byte(ret) != 0
}
func (c *defaultContext) LinkProgram(program uint32) {
purego.SyscallN(c.gpLinkProgram, uintptr(program))
}
func (c *defaultContext) PixelStorei(pname uint32, param int32) {
purego.SyscallN(c.gpPixelStorei, uintptr(pname), uintptr(param))
}
func (c *defaultContext) ReadPixels(dst []byte, x int32, y int32, width int32, height int32, format uint32, xtype uint32) {
purego.SyscallN(c.gpReadPixels, uintptr(x), uintptr(y), uintptr(width), uintptr(height), uintptr(format), uintptr(xtype), uintptr(unsafe.Pointer(&dst[0])))
}
func (c *defaultContext) RenderbufferStorage(target uint32, internalformat uint32, width int32, height int32) {
purego.SyscallN(c.gpRenderbufferStorage, uintptr(target), uintptr(internalformat), uintptr(width), uintptr(height))
}
func (c *defaultContext) Scissor(x int32, y int32, width int32, height int32) {
purego.SyscallN(c.gpScissor, uintptr(x), uintptr(y), uintptr(width), uintptr(height))
}
func (c *defaultContext) ShaderSource(shader uint32, xstring string) {
cstring, free := cStr(xstring)
defer free()
purego.SyscallN(c.gpShaderSource, uintptr(shader), 1, uintptr(unsafe.Pointer(&cstring)), 0)
}
func (c *defaultContext) StencilFunc(xfunc uint32, ref int32, mask uint32) {
purego.SyscallN(c.gpStencilFunc, uintptr(xfunc), uintptr(ref), uintptr(mask))
}
func (c *defaultContext) StencilOpSeparate(face uint32, fail uint32, zfail uint32, zpass uint32) {
purego.SyscallN(c.gpStencilOpSeparate, uintptr(face), uintptr(fail), uintptr(zfail), uintptr(zpass))
}
func (c *defaultContext) TexImage2D(target uint32, level int32, internalformat int32, width int32, height int32, format uint32, xtype uint32, pixels []byte) {
var ptr *byte
if len(pixels) > 0 {
ptr = &pixels[0]
}
purego.SyscallN(c.gpTexImage2D, uintptr(target), uintptr(level), uintptr(internalformat), uintptr(width), uintptr(height), 0, uintptr(format), uintptr(xtype), uintptr(unsafe.Pointer(ptr)))
runtime.KeepAlive(pixels)
}
func (c *defaultContext) TexParameteri(target uint32, pname uint32, param int32) {
purego.SyscallN(c.gpTexParameteri, uintptr(target), uintptr(pname), uintptr(param))
}
func (c *defaultContext) TexSubImage2D(target uint32, level int32, xoffset int32, yoffset int32, width int32, height int32, format uint32, xtype uint32, pixels []byte) {
purego.SyscallN(c.gpTexSubImage2D, uintptr(target), uintptr(level), uintptr(xoffset), uintptr(yoffset), uintptr(width), uintptr(height), uintptr(format), uintptr(xtype), uintptr(unsafe.Pointer(&pixels[0])))
runtime.KeepAlive(pixels)
}
func (c *defaultContext) Uniform1fv(location int32, value []float32) {
purego.SyscallN(c.gpUniform1fv, uintptr(location), uintptr(len(value)), uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) Uniform1i(location int32, v0 int32) {
purego.SyscallN(c.gpUniform1i, uintptr(location), uintptr(v0))
}
func (c *defaultContext) Uniform1iv(location int32, value []int32) {
purego.SyscallN(c.gpUniform1iv, uintptr(location), uintptr(len(value)), uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) Uniform2fv(location int32, value []float32) {
purego.SyscallN(c.gpUniform2fv, uintptr(location), uintptr(len(value)/2), uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) Uniform2iv(location int32, value []int32) {
purego.SyscallN(c.gpUniform2iv, uintptr(location), uintptr(len(value)/2), uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) Uniform3fv(location int32, value []float32) {
purego.SyscallN(c.gpUniform3fv, uintptr(location), uintptr(len(value)/3), uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) Uniform3iv(location int32, value []int32) {
purego.SyscallN(c.gpUniform3iv, uintptr(location), uintptr(len(value)/3), uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) Uniform4fv(location int32, value []float32) {
purego.SyscallN(c.gpUniform4fv, uintptr(location), uintptr(len(value)/4), uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) Uniform4iv(location int32, value []int32) {
purego.SyscallN(c.gpUniform4iv, uintptr(location), uintptr(len(value)/4), uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) UniformMatrix2fv(location int32, value []float32) {
purego.SyscallN(c.gpUniformMatrix2fv, uintptr(location), uintptr(len(value)/4), 0, uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) UniformMatrix3fv(location int32, value []float32) {
purego.SyscallN(c.gpUniformMatrix3fv, uintptr(location), uintptr(len(value)/9), 0, uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) UniformMatrix4fv(location int32, value []float32) {
purego.SyscallN(c.gpUniformMatrix4fv, uintptr(location), uintptr(len(value)/16), 0, uintptr(unsafe.Pointer(&value[0])))
runtime.KeepAlive(value)
}
func (c *defaultContext) UseProgram(program uint32) {
purego.SyscallN(c.gpUseProgram, uintptr(program))
}
func (c *defaultContext) VertexAttribPointer(index uint32, size int32, xtype uint32, normalized bool, stride int32, offset int) {
purego.SyscallN(c.gpVertexAttribPointer, uintptr(index), uintptr(size), uintptr(xtype), uintptr(boolToInt(normalized)), uintptr(stride), uintptr(offset))
}
func (c *defaultContext) Viewport(x int32, y int32, width int32, height int32) {
purego.SyscallN(c.gpViewport, uintptr(x), uintptr(y), uintptr(width), uintptr(height))
}
func (c *defaultContext) LoadFunctions() error {
g := procAddressGetter{ctx: c}
c.gpActiveTexture = g.get("glActiveTexture")
c.gpAttachShader = g.get("glAttachShader")
c.gpBindAttribLocation = g.get("glBindAttribLocation")
c.gpBindBuffer = g.get("glBindBuffer")
c.gpBindFramebuffer = g.get("glBindFramebuffer")
c.gpBindRenderbuffer = g.get("glBindRenderbuffer")
c.gpBindTexture = g.get("glBindTexture")
c.gpBindVertexArray = g.get("glBindVertexArray")
c.gpBlendEquationSeparate = g.get("glBlendEquationSeparate")
c.gpBlendFuncSeparate = g.get("glBlendFuncSeparate")
c.gpBufferData = g.get("glBufferData")
c.gpBufferSubData = g.get("glBufferSubData")
c.gpCheckFramebufferStatus = g.get("glCheckFramebufferStatus")
c.gpClear = g.get("glClear")
c.gpColorMask = g.get("glColorMask")
c.gpCompileShader = g.get("glCompileShader")
c.gpCreateProgram = g.get("glCreateProgram")
c.gpCreateShader = g.get("glCreateShader")
c.gpDeleteBuffers = g.get("glDeleteBuffers")
c.gpDeleteFramebuffers = g.get("glDeleteFramebuffers")
c.gpDeleteProgram = g.get("glDeleteProgram")
c.gpDeleteRenderbuffers = g.get("glDeleteRenderbuffers")
c.gpDeleteShader = g.get("glDeleteShader")
c.gpDeleteTextures = g.get("glDeleteTextures")
c.gpDeleteVertexArrays = g.get("glDeleteVertexArrays")
c.gpDisable = g.get("glDisable")
c.gpDisableVertexAttribArray = g.get("glDisableVertexAttribArray")
c.gpDrawElements = g.get("glDrawElements")
c.gpEnable = g.get("glEnable")
c.gpEnableVertexAttribArray = g.get("glEnableVertexAttribArray")
c.gpFlush = g.get("glFlush")
c.gpFramebufferRenderbuffer = g.get("glFramebufferRenderbuffer")
c.gpFramebufferTexture2D = g.get("glFramebufferTexture2D")
c.gpGenBuffers = g.get("glGenBuffers")
c.gpGenFramebuffers = g.get("glGenFramebuffers")
c.gpGenRenderbuffers = g.get("glGenRenderbuffers")
c.gpGenTextures = g.get("glGenTextures")
c.gpGenVertexArrays = g.get("glGenVertexArrays")
c.gpGetError = g.get("glGetError")
c.gpGetIntegerv = g.get("glGetIntegerv")
c.gpGetProgramInfoLog = g.get("glGetProgramInfoLog")
c.gpGetProgramiv = g.get("glGetProgramiv")
c.gpGetShaderInfoLog = g.get("glGetShaderInfoLog")
c.gpGetShaderiv = g.get("glGetShaderiv")
c.gpGetUniformLocation = g.get("glGetUniformLocation")
c.gpIsFramebuffer = g.get("glIsFramebuffer")
c.gpIsProgram = g.get("glIsProgram")
c.gpIsRenderbuffer = g.get("glIsRenderbuffer")
c.gpLinkProgram = g.get("glLinkProgram")
c.gpPixelStorei = g.get("glPixelStorei")
c.gpReadPixels = g.get("glReadPixels")
c.gpRenderbufferStorage = g.get("glRenderbufferStorage")
c.gpScissor = g.get("glScissor")
c.gpShaderSource = g.get("glShaderSource")
c.gpStencilFunc = g.get("glStencilFunc")
c.gpStencilOpSeparate = g.get("glStencilOpSeparate")
c.gpTexImage2D = g.get("glTexImage2D")
c.gpTexParameteri = g.get("glTexParameteri")
c.gpTexSubImage2D = g.get("glTexSubImage2D")
c.gpUniform1fv = g.get("glUniform1fv")
c.gpUniform1i = g.get("glUniform1i")
c.gpUniform1iv = g.get("glUniform1iv")
c.gpUniform2fv = g.get("glUniform2fv")
c.gpUniform2iv = g.get("glUniform2iv")
c.gpUniform3fv = g.get("glUniform3fv")
c.gpUniform3iv = g.get("glUniform3iv")
c.gpUniform4fv = g.get("glUniform4fv")
c.gpUniform4iv = g.get("glUniform4iv")
c.gpUniformMatrix2fv = g.get("glUniformMatrix2fv")
c.gpUniformMatrix3fv = g.get("glUniformMatrix3fv")
c.gpUniformMatrix4fv = g.get("glUniformMatrix4fv")
c.gpUseProgram = g.get("glUseProgram")
c.gpVertexAttribPointer = g.get("glVertexAttribPointer")
c.gpViewport = g.get("glViewport")
return g.error()
}
// cStr takes a Go string (with or without null-termination)
// and returns the C counterpart.
//
// The returned free function must be called once you are done using the string
// in order to free the memory.
func cStr(str string) (cstr *byte, free func()) {
bs := []byte(str)
if len(bs) == 0 || bs[len(bs)-1] != 0 {
bs = append(bs, 0)
}
return &bs[0], func() {
runtime.KeepAlive(bs)
bs = nil
}
}