func ImageData(img image.Image) (gl.Sizei, gl.Sizei, gl.Enum, gl.Enum, gl.Pointer) {
switch img := img.(type) {
case *image.NRGBA:
return gl.Sizei(img.Rect.Dx()), gl.Sizei(img.Rect.Dy()), gl.RGBA, gl.UNSIGNED_BYTE, gl.Pointer(&img.Pix[0])
case *image.RGBA:
return gl.Sizei(img.Rect.Dx()), gl.Sizei(img.Rect.Dy()), gl.RGBA, gl.UNSIGNED_BYTE, gl.Pointer(&img.Pix[0])
default:
panic(reflect.TypeOf(img))
}
return 0, 0, gl.RGB, gl.UNSIGNED_BYTE, nil
}
func ArrayPtr(data interface{}) (gl.Pointer, gl.Sizeiptr) {
var size gl.Sizeiptr
var ptr gl.Pointer
switch data := data.(type) {
case []float64:
duplicate := make([]gl.Float, len(data))
for i, v := range data {
duplicate[i] = gl.Float(v)
}
ptr, size = ArrayPtr(duplicate)
case []float32:
if len(data) == 0 {
size = 0
ptr = gl.Pointer(nil)
} else {
var v float32
size = gl.Sizeiptr(len(data) * int(unsafe.Sizeof(v)))
ptr = gl.Pointer(&data[0])
}
case []gl.Float:
if len(data) == 0 {
size = 0
ptr = gl.Pointer(nil)
} else {
var v gl.Float
size = gl.Sizeiptr(len(data) * int(unsafe.Sizeof(v)))
ptr = gl.Pointer(&data[0])
}
case []int16:
if len(data) == 0 {
size = 0
ptr = gl.Pointer(nil)
} else {
var v int16
size = gl.Sizeiptr(len(data) * int(unsafe.Sizeof(v)))
ptr = gl.Pointer(&data[0])
}
case []gl.Ushort:
if len(data) == 0 {
size = 0
ptr = gl.Pointer(nil)
} else {
var v gl.Ushort
size = gl.Sizeiptr(len(data) * int(unsafe.Sizeof(v)))
ptr = gl.Pointer(&data[0])
}
case []int:
duplicate := make([]gl.Ushort, len(data))
for i, v := range data {
duplicate[i] = gl.Ushort(v)
}
ptr, size = ArrayPtr(duplicate)
case []gl.Int:
if len(data) == 0 {
size = 0
ptr = gl.Pointer(nil)
} else {
var v gl.Int
size = gl.Sizeiptr(len(data) * int(unsafe.Sizeof(v)))
ptr = gl.Pointer(&data[0])
}
default:
panic(fmt.Sprintln("unknown data type:", reflect.TypeOf(data)))
}
return ptr, size
}