482 lines
13 KiB
Go
482 lines
13 KiB
Go
package goglbackend
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import (
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"fmt"
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"image/color"
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"math"
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"github.com/go-gl/gl/v3.2-core/gl"
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"github.com/tfriedel6/canvas/backend/backendbase"
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)
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const alphaTexSize = 2048
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var zeroes [alphaTexSize]byte
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type GoGLBackend struct {
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x, y, w, h int
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fx, fy, fw, fh float64
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buf uint32
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shadowBuf uint32
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alphaTex uint32
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sr solidShader
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lgr linearGradientShader
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rgr radialGradientShader
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ipr imagePatternShader
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sar solidAlphaShader
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rgar radialGradientAlphaShader
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lgar linearGradientAlphaShader
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ipar imagePatternAlphaShader
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ir imageShader
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gauss15r gaussianShader
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gauss63r gaussianShader
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gauss127r gaussianShader
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offscr1 offscreenBuffer
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offscr2 offscreenBuffer
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imageBufTex uint32
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imageBuf []byte
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ptsBuf []float32
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offscreen bool
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offscrBuf offscreenBuffer
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offscrImg Image
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glChan chan func()
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}
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type offscreenBuffer struct {
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tex uint32
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w int
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h int
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renderStencilBuf uint32
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frameBuf uint32
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alpha bool
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}
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func New(x, y, w, h int) (*GoGLBackend, error) {
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err := gl.Init()
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if err != nil {
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return nil, err
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}
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gl.GetError() // clear error state
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b := &GoGLBackend{
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w: w,
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h: h,
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fw: float64(w),
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fh: float64(h),
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ptsBuf: make([]float32, 0, 4096),
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}
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err = loadShader(solidVS, solidFS, &b.sr.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.sr.shaderProgram.mustLoadLocations(&b.sr)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(linearGradientVS, linearGradientFS, &b.lgr.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.lgr.shaderProgram.mustLoadLocations(&b.lgr)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(radialGradientVS, radialGradientFS, &b.rgr.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.rgr.shaderProgram.mustLoadLocations(&b.rgr)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(imagePatternVS, imagePatternFS, &b.ipr.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.ipr.shaderProgram.mustLoadLocations(&b.ipr)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(solidAlphaVS, solidAlphaFS, &b.sar.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.sar.shaderProgram.mustLoadLocations(&b.sar)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(linearGradientAlphaVS, linearGradientFS, &b.lgar.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.lgar.shaderProgram.mustLoadLocations(&b.lgar)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(radialGradientAlphaVS, radialGradientAlphaFS, &b.rgar.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.rgar.shaderProgram.mustLoadLocations(&b.rgar)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(imagePatternAlphaVS, imagePatternAlphaFS, &b.ipar.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.ipar.shaderProgram.mustLoadLocations(&b.ipar)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(imageVS, imageFS, &b.ir.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.ir.shaderProgram.mustLoadLocations(&b.ir)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(gaussian15VS, gaussian15FS, &b.gauss15r.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.gauss15r.shaderProgram.mustLoadLocations(&b.gauss15r)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(gaussian63VS, gaussian63FS, &b.gauss63r.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.gauss63r.shaderProgram.mustLoadLocations(&b.gauss63r)
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if err = glError(); err != nil {
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return nil, err
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}
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err = loadShader(gaussian127VS, gaussian127FS, &b.gauss127r.shaderProgram)
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if err != nil {
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return nil, err
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}
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b.gauss127r.shaderProgram.mustLoadLocations(&b.gauss127r)
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if err = glError(); err != nil {
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return nil, err
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}
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gl.GenBuffers(1, &b.buf)
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if err = glError(); err != nil {
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return nil, err
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}
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gl.GenBuffers(1, &b.shadowBuf)
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if err = glError(); err != nil {
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return nil, err
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}
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gl.ActiveTexture(gl.TEXTURE0)
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gl.GenTextures(1, &b.alphaTex)
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gl.BindTexture(gl.TEXTURE_2D, b.alphaTex)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
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gl.TexImage2D(gl.TEXTURE_2D, 0, gl.ALPHA, alphaTexSize, alphaTexSize, 0, gl.ALPHA, gl.UNSIGNED_BYTE, nil)
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gl.Enable(gl.BLEND)
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gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
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gl.Enable(gl.STENCIL_TEST)
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gl.StencilMask(0xFF)
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gl.Clear(gl.STENCIL_BUFFER_BIT)
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gl.StencilOp(gl.KEEP, gl.KEEP, gl.KEEP)
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gl.StencilFunc(gl.EQUAL, 0, 0xFF)
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gl.Disable(gl.SCISSOR_TEST)
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return b, nil
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}
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func NewOffscreen(w, h int, alpha bool) (*GoGLBackend, error) {
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b, err := New(0, 0, w, h)
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if err != nil {
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return nil, err
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}
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b.offscreen = true
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b.offscrBuf.alpha = alpha
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return b, nil
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}
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// SetBounds updates the bounds of the canvas. This would
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// usually be called for example when the window is resized
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func (b *GoGLBackend) SetBounds(x, y, w, h int) {
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if !b.offscreen {
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b.x, b.y = x, y
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b.fx, b.fy = float64(x), float64(y)
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}
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b.w, b.h = w, h
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b.fw, b.fh = float64(w), float64(h)
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}
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func (b *GoGLBackend) Size() (int, int) {
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return b.w, b.h
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}
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func glError() error {
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glErr := gl.GetError()
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if glErr != gl.NO_ERROR {
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return fmt.Errorf("GL Error: %x", glErr)
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}
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return nil
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}
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var activeContext *GoGLBackend
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func (b *GoGLBackend) activate() {
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if activeContext != b {
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activeContext = b
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if b.offscreen {
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gl.Viewport(0, 0, int32(b.w), int32(b.h))
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b.enableTextureRenderTarget(&b.offscrBuf)
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b.offscrImg.w = b.offscrBuf.w
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b.offscrImg.h = b.offscrBuf.h
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b.offscrImg.tex = b.offscrBuf.tex
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} else {
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gl.Viewport(int32(b.x), int32(b.y), int32(b.w), int32(b.h))
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b.disableTextureRenderTarget()
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}
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}
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loop:
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for {
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select {
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case f := <-b.glChan:
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f()
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default:
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break loop
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}
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}
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}
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func (b *GoGLBackend) DeleteOffscreen() {
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if !b.offscreen {
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return
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}
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gl.DeleteTextures(1, &b.offscrBuf.tex)
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gl.DeleteFramebuffers(1, &b.offscrBuf.frameBuf)
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gl.DeleteRenderbuffers(1, &b.offscrBuf.renderStencilBuf)
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b.offscreen = false
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b.activate()
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}
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type glColor struct {
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r, g, b, a float64
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}
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func colorGoToGL(c color.RGBA) glColor {
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var glc glColor
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glc.r = float64(c.R) / 255
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glc.g = float64(c.G) / 255
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glc.b = float64(c.B) / 255
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glc.a = float64(c.A) / 255
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return glc
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}
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func (b *GoGLBackend) useShader(style *backendbase.FillStyle) (vertexLoc uint32) {
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if lg := style.LinearGradient; lg != nil {
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lg := lg.(*LinearGradient)
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gl.ActiveTexture(gl.TEXTURE0)
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gl.BindTexture(gl.TEXTURE_2D, lg.tex)
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gl.UseProgram(b.lgr.ID)
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from := vec{style.Gradient.X0, style.Gradient.Y0}
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to := vec{style.Gradient.X1, style.Gradient.Y1}
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dir := to.sub(from)
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length := dir.len()
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dir = dir.scale(1 / length)
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gl.Uniform2f(b.lgr.CanvasSize, float32(b.fw), float32(b.fh))
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gl.Uniform2f(b.lgr.From, float32(from[0]), float32(from[1]))
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gl.Uniform2f(b.lgr.Dir, float32(dir[0]), float32(dir[1]))
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gl.Uniform1f(b.lgr.Len, float32(length))
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gl.Uniform1i(b.lgr.Gradient, 0)
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gl.Uniform1f(b.lgr.GlobalAlpha, float32(style.Color.A)/255)
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return b.lgr.Vertex
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}
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if rg := style.RadialGradient; rg != nil {
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rg := rg.(*RadialGradient)
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gl.ActiveTexture(gl.TEXTURE0)
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gl.BindTexture(gl.TEXTURE_2D, rg.tex)
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gl.UseProgram(b.rgr.ID)
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from := vec{style.Gradient.X0, style.Gradient.Y0}
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to := vec{style.Gradient.X1, style.Gradient.Y1}
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gl.Uniform2f(b.rgr.CanvasSize, float32(b.fw), float32(b.fh))
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gl.Uniform2f(b.rgr.From, float32(from[0]), float32(from[1]))
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gl.Uniform2f(b.rgr.To, float32(to[0]), float32(to[1]))
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gl.Uniform1f(b.rgr.RadFrom, float32(style.Gradient.RadFrom))
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gl.Uniform1f(b.rgr.RadTo, float32(style.Gradient.RadTo))
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gl.Uniform1i(b.rgr.Gradient, 0)
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gl.Uniform1f(b.rgr.GlobalAlpha, float32(style.Color.A)/255)
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return b.rgr.Vertex
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}
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if img := style.Image; img != nil {
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img := img.(*Image)
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gl.UseProgram(b.ipr.ID)
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gl.ActiveTexture(gl.TEXTURE0)
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gl.BindTexture(gl.TEXTURE_2D, img.tex)
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gl.Uniform2f(b.ipr.CanvasSize, float32(b.fw), float32(b.fh))
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gl.Uniform2f(b.ipr.ImageSize, float32(img.w), float32(img.h))
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gl.Uniform1i(b.ipr.Image, 0)
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gl.Uniform1f(b.ipr.GlobalAlpha, float32(style.Color.A)/255)
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return b.ipr.Vertex
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}
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gl.UseProgram(b.sr.ID)
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gl.Uniform2f(b.sr.CanvasSize, float32(b.fw), float32(b.fh))
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c := colorGoToGL(style.Color)
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gl.Uniform4f(b.sr.Color, float32(c.r), float32(c.g), float32(c.b), float32(c.a))
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gl.Uniform1f(b.sr.GlobalAlpha, 1)
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return b.sr.Vertex
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}
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func (b *GoGLBackend) useAlphaShader(style *backendbase.FillStyle, alphaTexSlot int32) (vertexLoc, alphaTexCoordLoc uint32) {
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if lg := style.LinearGradient; lg != nil {
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lg := lg.(*LinearGradient)
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gl.ActiveTexture(gl.TEXTURE0)
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gl.BindTexture(gl.TEXTURE_2D, lg.tex)
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gl.UseProgram(b.lgar.ID)
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from := vec{style.Gradient.X0, style.Gradient.Y0}
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to := vec{style.Gradient.X1, style.Gradient.Y1}
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dir := to.sub(from)
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length := dir.len()
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dir = dir.scale(1 / length)
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gl.Uniform2f(b.lgar.CanvasSize, float32(b.fw), float32(b.fh))
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gl.Uniform2f(b.lgar.From, float32(from[0]), float32(from[1]))
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gl.Uniform2f(b.lgar.Dir, float32(dir[0]), float32(dir[1]))
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gl.Uniform1f(b.lgar.Len, float32(length))
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gl.Uniform1i(b.lgar.Gradient, 0)
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gl.Uniform1i(b.lgar.AlphaTex, alphaTexSlot)
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gl.Uniform1f(b.lgar.GlobalAlpha, float32(style.Color.A)/255)
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return b.lgar.Vertex, b.lgar.AlphaTexCoord
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}
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if rg := style.RadialGradient; rg != nil {
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rg := rg.(*RadialGradient)
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gl.ActiveTexture(gl.TEXTURE0)
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gl.BindTexture(gl.TEXTURE_2D, rg.tex)
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gl.UseProgram(b.rgar.ID)
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from := vec{style.Gradient.X0, style.Gradient.Y0}
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to := vec{style.Gradient.X1, style.Gradient.Y1}
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gl.Uniform2f(b.rgar.CanvasSize, float32(b.fw), float32(b.fh))
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gl.Uniform2f(b.rgar.From, float32(from[0]), float32(from[1]))
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gl.Uniform2f(b.rgar.To, float32(to[0]), float32(to[1]))
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gl.Uniform1f(b.rgar.RadFrom, float32(style.Gradient.RadFrom))
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gl.Uniform1f(b.rgar.RadTo, float32(style.Gradient.RadTo))
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gl.Uniform1i(b.rgar.Gradient, 0)
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gl.Uniform1i(b.rgar.AlphaTex, alphaTexSlot)
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gl.Uniform1f(b.rgar.GlobalAlpha, float32(style.Color.A)/255)
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return b.rgar.Vertex, b.rgar.AlphaTexCoord
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}
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if img := style.Image; img != nil {
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img := img.(*Image)
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gl.UseProgram(b.ipar.ID)
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gl.ActiveTexture(gl.TEXTURE0)
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gl.BindTexture(gl.TEXTURE_2D, img.tex)
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gl.Uniform2f(b.ipar.CanvasSize, float32(b.fw), float32(b.fh))
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gl.Uniform2f(b.ipar.ImageSize, float32(img.w), float32(img.h))
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gl.Uniform1i(b.ipar.Image, 0)
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gl.Uniform1i(b.ipar.AlphaTex, alphaTexSlot)
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gl.Uniform1f(b.ipar.GlobalAlpha, float32(style.Color.A)/255)
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return b.ipar.Vertex, b.ipar.AlphaTexCoord
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}
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gl.UseProgram(b.sar.ID)
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gl.Uniform2f(b.sar.CanvasSize, float32(b.fw), float32(b.fh))
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c := colorGoToGL(style.Color)
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gl.Uniform4f(b.sar.Color, float32(c.r), float32(c.g), float32(c.b), float32(c.a))
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gl.Uniform1i(b.sar.AlphaTex, alphaTexSlot)
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gl.Uniform1f(b.sar.GlobalAlpha, 1)
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return b.sar.Vertex, b.sar.AlphaTexCoord
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}
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func (b *GoGLBackend) enableTextureRenderTarget(offscr *offscreenBuffer) {
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if offscr.w != b.w || offscr.h != b.h {
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if offscr.w != 0 && offscr.h != 0 {
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gl.DeleteTextures(1, &offscr.tex)
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gl.DeleteFramebuffers(1, &offscr.frameBuf)
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gl.DeleteRenderbuffers(1, &offscr.renderStencilBuf)
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}
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offscr.w = b.w
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offscr.h = b.h
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gl.ActiveTexture(gl.TEXTURE0)
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gl.GenTextures(1, &offscr.tex)
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gl.BindTexture(gl.TEXTURE_2D, offscr.tex)
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// todo do non-power-of-two textures work everywhere?
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if offscr.alpha {
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gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, int32(b.w), int32(b.h), 0, gl.RGBA, gl.UNSIGNED_BYTE, nil)
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} else {
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gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGB, int32(b.w), int32(b.h), 0, gl.RGB, gl.UNSIGNED_BYTE, nil)
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}
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
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gl.GenFramebuffers(1, &offscr.frameBuf)
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gl.BindFramebuffer(gl.FRAMEBUFFER, offscr.frameBuf)
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gl.GenRenderbuffers(1, &offscr.renderStencilBuf)
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gl.BindRenderbuffer(gl.RENDERBUFFER, offscr.renderStencilBuf)
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gl.RenderbufferStorage(gl.RENDERBUFFER, gl.DEPTH24_STENCIL8, int32(b.w), int32(b.h))
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gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.RENDERBUFFER, offscr.renderStencilBuf)
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gl.FramebufferTexture(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, offscr.tex, 0)
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if err := gl.CheckFramebufferStatus(gl.FRAMEBUFFER); err != gl.FRAMEBUFFER_COMPLETE {
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// todo this should maybe not panic
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panic(fmt.Sprintf("Failed to set up framebuffer for offscreen texture: %x", err))
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}
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gl.Clear(gl.COLOR_BUFFER_BIT | gl.STENCIL_BUFFER_BIT)
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} else {
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|
gl.BindFramebuffer(gl.FRAMEBUFFER, offscr.frameBuf)
|
|
}
|
|
}
|
|
|
|
func (b *GoGLBackend) disableTextureRenderTarget() {
|
|
if b.offscreen {
|
|
b.enableTextureRenderTarget(&b.offscrBuf)
|
|
} else {
|
|
gl.BindFramebuffer(gl.FRAMEBUFFER, 0)
|
|
}
|
|
}
|
|
|
|
type vec [2]float64
|
|
|
|
func (v1 vec) sub(v2 vec) vec {
|
|
return vec{v1[0] - v2[0], v1[1] - v2[1]}
|
|
}
|
|
|
|
func (v vec) len() float64 {
|
|
return math.Sqrt(v[0]*v[0] + v[1]*v[1])
|
|
}
|
|
|
|
func (v vec) scale(f float64) vec {
|
|
return vec{v[0] * f, v[1] * f}
|
|
}
|