func createShader(name string, shaderType int) (gl.Uint, error) {
data, err := fileRead(name)
if err != nil {
return 0, err
}
if len(data) == 0 {
return 0, errors.New("No shader code.")
}
var shader gl.Uint
switch shaderType {
case VertexShaderType:
shader = gl.CreateShader(gl.VERTEX_SHADER)
case FragmentShaderType:
shader = gl.CreateShader(gl.FRAGMENT_SHADER)
default:
return 0, errors.New("Unknown ShaderType.")
}
src := gl.GLStringArray(string(data))
defer gl.GLStringArrayFree(src)
gl.ShaderSource(shader, gl.Sizei(1), &src[0], nil)
gl.CompileShader(shader)
// Similar to print_log in the C code example
var length gl.Int
gl.GetShaderiv(shader, gl.INFO_LOG_LENGTH, &length)
if length > 1 {
glString := gl.GLStringAlloc(gl.Sizei(length))
defer gl.GLStringFree(glString)
gl.GetShaderInfoLog(shader, gl.Sizei(length), nil, glString)
return 0, errors.New(fmt.Sprintf("Shader log: %s", gl.GoString(glString)))
}
return shader, nil
}
func initResources() {
var compileOk gl.Int
// Vertex Shader
vs = gl.CreateShader(gl.VERTEX_SHADER)
vsSrc := gl.GLStringArray(vsSource)
defer gl.GLStringArrayFree(vsSrc)
gl.ShaderSource(vs, gl.Sizei(len(vsSrc)), &vsSrc[0], nil)
gl.CompileShader(vs)
gl.GetShaderiv(vs, gl.COMPILE_STATUS, &compileOk)
if compileOk == 0 {
errNum := gl.GetError()
fmt.Printf("Error in vertex shader: %d\n", errNum)
}
// Fragment Shader
fs = gl.CreateShader(gl.FRAGMENT_SHADER)
fsSrc := gl.GLStringArray(fsSource)
defer gl.GLStringArrayFree(fsSrc)
gl.ShaderSource(fs, gl.Sizei(1), &fsSrc[0], nil)
gl.CompileShader(fs)
gl.GetShaderiv(fs, gl.COMPILE_STATUS, &compileOk)
if compileOk == 0 {
errNum := gl.GetError()
fmt.Printf("Error in fragment shader: %d\n", errNum)
}
// GLSL program
program = gl.CreateProgram()
gl.AttachShader(program, vs)
gl.AttachShader(program, fs)
gl.LinkProgram(program)
gl.GetProgramiv(program, gl.LINK_STATUS, &compileOk)
if compileOk == 0 {
fmt.Printf("Error in program.\n")
}
// Get the attribute location from the GLSL program (here from the vertex shader)
attributeName := gl.GLString("coord2d")
defer gl.GLStringFree(attributeName)
attributeTemp := gl.GetAttribLocation(program, attributeName)
if attributeTemp == -1 {
fmt.Printf("Could not bind attribute %s\n", gl.GoString(attributeName))
}
attributeCoord2d = gl.Uint(attributeTemp)
}
func LoadShader(data string, shaderType ShaderType) (*Shader, error) {
var id gl.Uint
switch shaderType {
case VertexShader:
id = gl.CreateShader(gl.VERTEX_SHADER)
case FragmentShader:
id = gl.CreateShader(gl.FRAGMENT_SHADER)
default:
return nil, ErrUnknownShader
}
shader := &Shader{id: id}
src := gl.GLStringArray(data)
length := gl.Int(-1)
gl.ShaderSource(shader.id, gl.Sizei(1), &src[0], &length)
gl.GLStringArrayFree(src)
return shader, nil
}