func ReadAlpha(image *image.Alpha) {
alignment := C.GLint(0)
C.glGetIntegerv(C.GL_PACK_ALIGNMENT, &alignment)
align := C.GLint(1)
for align < alignment && image.Stride%(int(align)*2) == 0 {
align *= 2
}
// need smaller alignment
if align < alignment {
C.glPixelStorei(C.GL_PACK_ALIGNMENT, align)
}
C.glReadPixels(C.GLint(image.Rect.Min.X), C.GLint(image.Rect.Min.Y),
C.GLsizei(image.Rect.Dx()), C.GLsizei(image.Rect.Dy()),
C.GL_ALPHA, C.GL_UNSIGNED_BYTE, unsafe.Pointer(&image.Pix[0]))
// restore alignment
if align < alignment {
C.glPixelStorei(C.GL_PACK_ALIGNMENT, alignment)
}
}
// TexImage2DFromImage loads texture data from an image.Image into the currently
// bound GL texture using the glTexImage2D call. If you wish to load only part of
// an image, pass a subimage as the argument.
//
// Precondition: no buffer object bound to PIXEL_UNPACK_BUFFER
//
// Additional state modified: UNPACK_ALIGNMENT, UNPACK_ROW_LENGTH
func TexImage2DFromImage(target GLenum, level int, internalformat int, border int, img image.Image) {
bounds := img.Bounds()
if bounds.Empty() {
return
}
info := getImageInfo(img)
C.glPixelStorei(C.GLenum(gl.UNPACK_ALIGNMENT), C.GLint(1))
C.glPixelStorei(C.GLenum(gl.UNPACK_ROW_LENGTH), C.GLint(info.RowLength))
C.glTexImage2D(C.GLenum(target), C.GLint(level), C.GLint(internalformat),
C.GLsizei(bounds.Dx()), C.GLsizei(bounds.Dy()), C.GLint(border),
C.GLenum(info.Format), C.GLenum(info.Type),
info.Data)
}
// TexSubImage2DFromImage loads texture data from an image.Image into the currently
// bound GL texture using the glTexSubImage2D call. If you wish to load only part of
// an image, pass a subimage as the argument.
//
// Precondition: no buffer object bound to PIXEL_UNPACK_BUFFER
//
// Additional state modified: UNPACK_ALIGNMENT, UNPACK_ROW_LENGTH
func TexSubImage2DFromImage(target GLenum, level int, dest image.Rectangle, img image.Image) {
bounds := img.Bounds()
if dest.Dx() > bounds.Dx() || dest.Dy() > bounds.Dy() {
return
}
info := getImageInfo(img)
C.glPixelStorei(C.GLenum(gl.UNPACK_ALIGNMENT), C.GLint(1))
C.glPixelStorei(C.GLenum(gl.UNPACK_ROW_LENGTH), C.GLint(info.RowLength))
C.glTexSubImage2D(C.GLenum(target), C.GLint(level),
C.GLint(dest.Min.X), C.GLint(dest.Min.Y),
C.GLsizei(dest.Dx()), C.GLsizei(dest.Dy()),
C.GLenum(info.Format), C.GLenum(info.Type),
info.Data)
}
func PixelStorei(pname Enum, param int32) {
defer func() {
errstr := errDrain()
log.Printf("gl.PixelStorei(%v, %v) %v", pname, param, errstr)
}()
C.glPixelStorei(pname.c(), C.GLint(param))
}
func ReadRGBA(image *image.NRGBA) {
alignment := C.GLint(0)
C.glGetIntegerv(C.GL_PACK_ALIGNMENT, &alignment)
align := image.Stride % int(alignment) // align: 4 or 0
// need smaller alignment
if align > 0 {
C.glPixelStorei(C.GL_PACK_ALIGNMENT, C.GLint(align))
}
C.glReadPixels(C.GLint(image.Rect.Min.X), C.GLint(image.Rect.Min.Y),
C.GLsizei(image.Rect.Dx()), C.GLsizei(image.Rect.Dy()),
C.GL_RGBA, C.GL_UNSIGNED_BYTE, unsafe.Pointer(&image.Pix[0]))
// restore alignment
if align > 0 {
C.glPixelStorei(C.GL_PACK_ALIGNMENT, alignment)
}
}
func adjustUnpackAlignment(stride int) C.GLint {
alignment := C.GLint(0)
C.glGetIntegerv(C.GL_UNPACK_ALIGNMENT, &alignment)
align := C.GLint(1)
for align < alignment && stride%(int(align)*2) == 0 {
align *= 2
}
// need smaller alignment
if align < alignment {
C.glPixelStorei(C.GL_UNPACK_ALIGNMENT, align)
// return old alignment
return alignment
} else {
return 0
}
}
func PixelStorei(pname Enum, param int32) {
C.glPixelStorei(pname.c(), C.GLint(param))
}
func PixelStorei(
pname Enum, param int32) {
C.glPixelStorei(
C.GLenum(pname),
C.GLint(param))
}
func PixelStorei(pname Packing, param int) {
C.glPixelStorei(C.GLenum(pname), C.GLint(param))
}
func restoreAlignment(alignment C.GLint) {
if alignment > 0 {
C.glPixelStorei(C.GL_UNPACK_ALIGNMENT, alignment)
}
}
func PixelStorei(pname, param uint) {
C.glPixelStorei(C.GLenum(pname), C.GLint(param))
}