ml
92 lines
2.3 KiB
Go
92 lines
2.3 KiB
Go
package graphics
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import "github.com/inkyblackness/hacked/ui/opengl"
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// BitmapTexture wraps an OpenGL handle for a downloaded image.
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type BitmapTexture struct {
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gl opengl.OpenGL
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handle uint32
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width, height float32
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u, v float32
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pixelData []byte
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}
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func powerOfTwo(value int) int {
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result := 2
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for (result < value) && (result < 0x1000) {
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result *= 2
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}
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return result
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}
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// NewBitmapTexture downloads the provided raw data to OpenGL and returns a BitmapTexture instance.
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func NewBitmapTexture(gl opengl.OpenGL, width, height int, pixelData []byte) *BitmapTexture {
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textureWidth := powerOfTwo(width)
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textureHeight := powerOfTwo(height)
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tex := &BitmapTexture{
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gl: gl,
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handle: gl.GenTextures(1)[0],
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width: float32(width),
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height: float32(height),
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pixelData: pixelData,
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}
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tex.u = tex.width / float32(textureWidth)
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tex.v = tex.height / float32(textureHeight)
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paddedData := make([]byte, textureWidth*textureHeight)
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for y := 0; y < height; y++ {
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inStart := y * width
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outOffset := y * textureWidth
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for x := 0; x < width; x++ {
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value := pixelData[inStart+x]
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paddedData[outOffset] = value
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outOffset++
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}
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}
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gl.BindTexture(opengl.TEXTURE_2D, tex.handle)
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gl.TexImage2D(opengl.TEXTURE_2D, 0, opengl.RED, int32(textureWidth), int32(textureHeight),
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0, opengl.RED, opengl.UNSIGNED_BYTE, paddedData)
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gl.TexParameteri(opengl.TEXTURE_2D, opengl.TEXTURE_MAG_FILTER, opengl.NEAREST)
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gl.TexParameteri(opengl.TEXTURE_2D, opengl.TEXTURE_MIN_FILTER, opengl.NEAREST)
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gl.GenerateMipmap(opengl.TEXTURE_2D)
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gl.BindTexture(opengl.TEXTURE_2D, 0)
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return tex
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}
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// Dispose releases the OpenGL texture.
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func (tex *BitmapTexture) Dispose() {
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if tex.handle != 0 {
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tex.gl.DeleteTextures([]uint32{tex.handle})
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tex.handle = 0
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}
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}
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// Handle returns the texture handle.
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func (tex *BitmapTexture) Handle() uint32 {
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return tex.handle
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}
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// PixelData returns the original paletted pixel data.
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func (tex *BitmapTexture) PixelData() []byte {
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return tex.pixelData
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}
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// Size returns the dimensions of the bitmap, in pixels.
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func (tex *BitmapTexture) Size() (width, height float32) {
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return tex.width, tex.height
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}
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// UV returns the maximum U and V values for the bitmap. The bitmap will be
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// stored in a power-of-two texture, which may be larger than the bitmap.
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func (tex *BitmapTexture) UV() (u, v float32) {
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return tex.u, tex.v
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}
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