func createTexture(r io.Reader) (gl.Texture, error) {
img, err := png.Decode(r)
if err != nil {
return gl.Texture(0), err
}
rgbaImg, ok := img.(*image.NRGBA)
if !ok {
return gl.Texture(0), errors.New("texture must be an NRGBA image")
}
textureId := gl.GenTexture()
textureId.Bind(gl.TEXTURE_2D)
gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
// flip image: first pixel is lower left corner
imgWidth, imgHeight := img.Bounds().Dx(), img.Bounds().Dy()
data := make([]byte, imgWidth*imgHeight*4)
lineLen := imgWidth * 4
dest := len(data) - lineLen
for src := 0; src < len(rgbaImg.Pix); src += rgbaImg.Stride {
copy(data[dest:dest+lineLen], rgbaImg.Pix[src:src+rgbaImg.Stride])
dest -= lineLen
}
gl.TexImage2D(gl.TEXTURE_2D, 0, 4, imgWidth, imgHeight, 0, gl.RGBA, gl.UNSIGNED_BYTE, data)
return textureId, nil
}
// NewAtlas will create a new atlas with enough space to
// at least nRows X nColumns chunks of widthXheight size. The total
// number of chunks are determinated by the power of two rule below.
//
// The actual memory used might be larger since all atlas MUST BE
// a power of 2 rect (16, 32, 64, 128...). But the rectangle used
// by the chunk is limited to width/height.
func NewAtlas(width, height, nRows, nColumns int) *Atlas {
_, max := minMaxOf(powerOfTwo(nRows*height), powerOfTwo(nColumns*width))
return &Atlas{
cw: width,
ch: height,
data: image.NewRGBA(image.Rect(0, 0, max, max)),
gltex: gl.Texture(gl.FALSE),
}
}
func (a *Atlas) unbind(release bool) error {
if !gl.Object(a.gltex).IsTexture() {
return nil
}
a.gltex.Unbind(gl.TEXTURE_2D)
if release {
a.gltex.Delete()
}
a.gltex = gl.Texture(gl.FALSE)
return checkGlError()
}
// Bind binds the texture
func (t *Texture) Bind(coordType CoordType) {
// ensureGlContext()
if t != nil && t.t != 0 {
// Bind the texture
t.t.Bind(gl.TEXTURE_2D)
// Check if we need to define a special texture matrix
if coordType == CoordPixels || t.pixelsFlipped {
matrix := [16]float32{1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1}
// If non-normalized coordinates (= pixels) are requested, we need to
// setup scale factors that convert the range [0 .. size] to [0 .. 1]
if coordType == CoordPixels {
matrix[0] = 1.0 / t.size.X
matrix[5] = 1.0 / t.size.Y
}
// If pixels are flipped we must invert the Y axis
if t.pixelsFlipped {
matrix[5] = -matrix[5]
matrix[13] = 1.0
}
// Load the matrix
gl.MatrixMode(gl.TEXTURE)
gl.LoadMatrixf(&matrix)
// Go back to model-view mode (sf::RenderTarget relies on it)
gl.MatrixMode(gl.MODELVIEW)
}
} else {
// Bind no texture
gl.Texture(0).Unbind(gl.TEXTURE_2D)
// Reset the texture matrix
gl.MatrixMode(gl.TEXTURE)
gl.LoadIdentity()
// Go back to model-view mode (sf::RenderTarget relies on it)
gl.MatrixMode(gl.MODELVIEW)
}
}
func TextureFromDDS(fname string) (gl.Texture, error) {
file, err := os.Open(fname)
if err != nil {
return gl.Texture(0), fmt.Errorf("Cannot open DDS file: %v", err)
}
defer file.Close()
var filecode [4]byte
binary.Read(file, binary.LittleEndian, &filecode) // DDS is always Little Endian encoded
if string(filecode[:]) != "DDS " {
return gl.Texture(0), fmt.Errorf("File code is not DDS, instead got %v.", string(filecode[:]))
}
header := ddsHeader{}
err = binary.Read(file, binary.LittleEndian, &header)
if err != nil {
return gl.Texture(0), fmt.Errorf("Couldn't read DDS header: %v", err)
}
stat, err := file.Stat()
if err != nil {
return gl.Texture(0), fmt.Errorf("Couldn't get size of file: %v", err)
}
// All of the file after the header and file identifier "DDS "
// is images. 4 byte identifier + 124 byte header = 128 bytes
// to take off the file size.
bufSize := stat.Size() - 128
buffer := make([]byte, bufSize)
err = binary.Read(file, binary.LittleEndian, buffer)
if err != nil {
return gl.Texture(0), fmt.Errorf("Couldn't read all mipmaps into buffer: %v", err)
}
//var components uint32
var blockSize uint32
var format gl.GLenum
switch header.PixelFormat.FourCC {
case fourCC_DXT1:
format = gl.COMPRESSED_RGBA_S3TC_DXT1_EXT
//components = 3
blockSize = 8
case fourCC_DXT3:
format = gl.COMPRESSED_RGBA_S3TC_DXT3_EXT
//components = 4
blockSize = 16
case fourCC_DXT5:
format = gl.COMPRESSED_RGBA_S3TC_DXT5_EXT
//components = 4
blockSize = 16
default:
return gl.Texture(0), fmt.Errorf("Invalid four CC in DDS header. Got: %x; Expected %x; %x; or %x", header.PixelFormat.FourCC, fourCC_DXT1, fourCC_DXT3, fourCC_DXT5)
}
offset := 0
tex := gl.GenTexture()
tex.Bind(gl.TEXTURE_2D)
gl.PixelStorei(gl.UNPACK_ALIGNMENT, 1)
for level, width, height := 0, header.Width, header.Height; level < int(header.MipMapCount) && (width > 0 || height > 0); level, width, height = level+1, width/2, height/2 {
size := int(((width + 3) / 4) * ((height + 3) / 4) * blockSize)
gl.CompressedTexImage2D(gl.TEXTURE_2D, level, format, int(width), int(height), 0, size, &buffer[offset])
offset += size
}
return tex, nil
}
