package goglbackend import ( "runtime" "github.com/tfriedel6/canvas/backend/backendbase" "github.com/tfriedel6/canvas/backend/gogl/gl" ) // LinearGradient is a gradient with any number of // stops and any number of colors. The gradient will // be drawn such that each point on the gradient // will correspond to a straight line type LinearGradient struct { gradient } // RadialGradient is a gradient with any number of // stops and any number of colors. The gradient will // be drawn such that each point on the gradient // will correspond to a circle type RadialGradient struct { gradient } type gradient struct { b *GoGLBackend tex uint32 loaded bool } func (b *GoGLBackend) LoadLinearGradient(data backendbase.Gradient) backendbase.LinearGradient { b.activate() lg := &LinearGradient{ gradient: gradient{b: b}, } gl.GenTextures(1, &lg.tex) gl.ActiveTexture(gl.TEXTURE0) gl.BindTexture(gl.TEXTURE_2D, lg.tex) gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR) gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR) gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE) gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE) lg.load(data) runtime.SetFinalizer(lg, func(lg *LinearGradient) { b.glChan <- func() { gl.DeleteTextures(1, &lg.tex) } }) return lg } func (b *GoGLBackend) LoadRadialGradient(data backendbase.Gradient) backendbase.RadialGradient { b.activate() rg := &RadialGradient{ gradient: gradient{b: b}, } gl.GenTextures(1, &rg.tex) gl.ActiveTexture(gl.TEXTURE0) gl.BindTexture(gl.TEXTURE_2D, rg.tex) gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR) gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR) gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE) gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE) rg.load(data) runtime.SetFinalizer(rg, func(rg *RadialGradient) { b.glChan <- func() { gl.DeleteTextures(1, &rg.tex) } }) return rg } // Delete explicitly deletes the gradient func (g *gradient) Delete() { g.b.activate() gl.DeleteTextures(1, &g.tex) } func (lg *LinearGradient) Replace(data backendbase.Gradient) { lg.load(data) } func (rg *RadialGradient) Replace(data backendbase.Gradient) { rg.load(data) } func (g *gradient) load(stops backendbase.Gradient) { if g.loaded { return } g.b.activate() gl.ActiveTexture(gl.TEXTURE0) gl.BindTexture(gl.TEXTURE_2D, g.tex) var pixels [2048 * 4]byte pp := 0 for i := 0; i < 2048; i++ { c := stops.ColorAt(float64(i) / 2047) pixels[pp] = c.R pixels[pp+1] = c.G pixels[pp+2] = c.B pixels[pp+3] = c.A pp += 4 } gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 2048, 1, 0, gl.RGBA, gl.UNSIGNED_BYTE, gl.Ptr(&pixels[0])) g.loaded = true }