func newProgram(vertexShaderSource, fragmentShaderSource string) (uint32, error) {
vertexShader, err := compileShader(vertexShaderSource, gl.VERTEX_SHADER)
if err != nil {
return 0, err
}
fragmentShader, err := compileShader(fragmentShaderSource, gl.FRAGMENT_SHADER)
if err != nil {
return 0, err
}
program := gl.CreateProgram()
gl.AttachShader(program, vertexShader)
gl.AttachShader(program, fragmentShader)
gl.LinkProgram(program)
var status int32
gl.GetProgramiv(program, gl.LINK_STATUS, &status)
if status == gl.FALSE {
var logLength int32
gl.GetProgramiv(program, gl.INFO_LOG_LENGTH, &logLength)
log := strings.Repeat("\x00", int(logLength+1))
gl.GetProgramInfoLog(program, logLength, nil, gl.Str(log))
return 0, fmt.Errorf("failed to link program: %v", log)
}
gl.DeleteShader(vertexShader)
gl.DeleteShader(fragmentShader)
return program, nil
}
func compileShader(source string, shaderType uint32) (uint32, error) {
shader := gl.CreateShader(shaderType)
csource := gl.Str(source)
gl.ShaderSource(shader, 1, &csource, nil)
gl.CompileShader(shader)
var status int32
gl.GetShaderiv(shader, gl.COMPILE_STATUS, &status)
if status == gl.FALSE {
var logLength int32
gl.GetShaderiv(shader, gl.INFO_LOG_LENGTH, &logLength)
log := strings.Repeat("\x00", int(logLength+1))
gl.GetShaderInfoLog(shader, logLength, nil, gl.Str(log))
return 0, fmt.Errorf("failed to compile %v: %v", source, log)
}
return shader, nil
}
func setupGL() int32 {
gl.Disable(gl.DEPTH_TEST)
gl.ClearColor(0.7, 0.7, 0.7, 1)
program, _ := loadResources()
gl.BindFragDataLocation(program, 0, gl.Str("outputColor\x00"))
cameraMatrixUniform := gl.GetUniformLocation(program, gl.Str("cameraMatrix\x00"))
octUniform := gl.GetUniformLocation(program, gl.Str("oct\x00"))
gl.Uniform1i(octUniform, 0)
gl.Viewport(0, 0, winWidth, winHeight)
var vao uint32
gl.GenVertexArrays(1, &vao)
gl.BindVertexArray(vao)
quadVertexBufferData := []float32{
-1, -1, 0,
1, -1, 0,
-1, 1, 0,
-1, 1, 0,
1, -1, 0,
1, 1, 0,
}
var vbo uint32
gl.GenBuffers(1, &vbo)
gl.BindBuffer(gl.ARRAY_BUFFER, vbo)
gl.BufferData(gl.ARRAY_BUFFER, len(quadVertexBufferData)*4, gl.Ptr(quadVertexBufferData), gl.STATIC_DRAW)
vertAttrib := uint32(gl.GetAttribLocation(program, gl.Str("inputPosition\x00")))
gl.EnableVertexAttribArray(vertAttrib)
gl.VertexAttribPointer(vertAttrib, 3, gl.FLOAT, false, 0, gl.PtrOffset(0))
return cameraMatrixUniform
}
// BindAttribLocation implements the opengl.OpenGl interface.
func (native *OpenGl) BindAttribLocation(program uint32, index uint32, name string) {
gl.BindAttribLocation(program, index, gl.Str(name+"\x00"))
}
// GetUniformLocation implements the opengl.OpenGl interface.
func (native *OpenGl) GetUniformLocation(program uint32, name string) int32 {
return gl.GetUniformLocation(program, gl.Str(name+"\x00"))
}
// GetShaderInfoLog implements the opengl.OpenGl interface.
func (native *OpenGl) GetShaderInfoLog(shader uint32) string {
logLength := native.GetShaderParameter(shader, gl.INFO_LOG_LENGTH)
log := strings.Repeat("\x00", int(logLength+1))
gl.GetShaderInfoLog(shader, logLength, nil, gl.Str(log))
return log
}
// GetProgramInfoLog implements the opengl.OpenGl interface.
func (native *OpenGl) GetProgramInfoLog(program uint32) string {
logLength := native.GetProgramParameter(program, gl.INFO_LOG_LENGTH)
log := strings.Repeat("\x00", int(logLength+1))
gl.GetProgramInfoLog(program, logLength, nil, gl.Str(log))
return log
}