package pixelgl import ( "fmt" "image/color" "github.com/faiface/glhf" "github.com/faiface/mainthread" "github.com/faiface/pixel" "github.com/go-gl/mathgl/mgl32" "github.com/pkg/errors" ) // Canvas is an off-screen rectangular BasicTarget and Picture at the same time, that you can draw // onto. // // It supports TrianglesPosition, TrianglesColor, TrianglesPicture and PictureColor. type Canvas struct { gf *GLFrame shader *glhf.Shader cmp pixel.ComposeMethod mat mgl32.Mat3 col mgl32.Vec4 smooth bool } var _ pixel.ComposeTarget = (*Canvas)(nil) // NewCanvas creates a new empty, fully transparent Canvas with given bounds. func NewCanvas(bounds pixel.Rect) *Canvas { c := &Canvas{ gf: NewGLFrame(bounds), mat: mgl32.Ident3(), col: mgl32.Vec4{1, 1, 1, 1}, } c.SetBounds(bounds) var shader *glhf.Shader mainthread.Call(func() { var err error shader, err = glhf.NewShader( canvasVertexFormat, canvasUniformFormat, canvasVertexShader, canvasFragmentShader, ) if err != nil { panic(errors.Wrap(err, "failed to create Canvas, there's a bug in the shader")) } }) c.shader = shader return c } // MakeTriangles creates a specialized copy of the supplied Triangles that draws onto this Canvas. // // TrianglesPosition, TrianglesColor and TrianglesPicture are supported. func (c *Canvas) MakeTriangles(t pixel.Triangles) pixel.TargetTriangles { return &canvasTriangles{ GLTriangles: NewGLTriangles(c.shader, t), dst: c, } } // MakePicture create a specialized copy of the supplied Picture that draws onto this Canvas. // // PictureColor is supported. func (c *Canvas) MakePicture(p pixel.Picture) pixel.TargetPicture { if cp, ok := p.(*canvasPicture); ok { return &canvasPicture{ GLPicture: cp.GLPicture, dst: c, } } if gp, ok := p.(GLPicture); ok { return &canvasPicture{ GLPicture: gp, dst: c, } } return &canvasPicture{ GLPicture: NewGLPicture(p), dst: c, } } // SetMatrix sets a Matrix that every point will be projected by. func (c *Canvas) SetMatrix(m pixel.Matrix) { for i := range m { c.mat[i] = float32(m[i]) } } // SetColorMask sets a color that every color in triangles or a picture will be multiplied by. func (c *Canvas) SetColorMask(col color.Color) { rgba := pixel.RGBA{R: 1, G: 1, B: 1, A: 1} if col != nil { rgba = pixel.ToRGBA(col) } c.col = mgl32.Vec4{ float32(rgba.R), float32(rgba.G), float32(rgba.B), float32(rgba.A), } } // SetComposeMethod sets a Porter-Duff composition method to be used in the following draws onto // this Canvas. func (c *Canvas) SetComposeMethod(cmp pixel.ComposeMethod) { c.cmp = cmp } // SetBounds resizes the Canvas to the new bounds. Old content will be preserved. func (c *Canvas) SetBounds(bounds pixel.Rect) { c.gf.SetBounds(bounds) } // Bounds returns the rectangular bounds of the Canvas. func (c *Canvas) Bounds() pixel.Rect { return c.gf.Bounds() } // SetSmooth sets whether stretched Pictures drawn onto this Canvas should be drawn smooth or // pixely. func (c *Canvas) SetSmooth(smooth bool) { c.smooth = smooth } // Smooth returns whether stretched Pictures drawn onto this Canvas are set to be drawn smooth or // pixely. func (c *Canvas) Smooth() bool { return c.smooth } // must be manually called inside mainthread func (c *Canvas) setGlhfBounds() { bx, by, bw, bh := intBounds(c.gf.Bounds()) glhf.Bounds(bx, by, bw, bh) } // must be manually called inside mainthread func setBlendFunc(cmp pixel.ComposeMethod) { switch cmp { case pixel.ComposeOver: glhf.BlendFunc(glhf.One, glhf.OneMinusSrcAlpha) case pixel.ComposeIn: glhf.BlendFunc(glhf.DstAlpha, glhf.Zero) case pixel.ComposeOut: glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.Zero) case pixel.ComposeAtop: glhf.BlendFunc(glhf.DstAlpha, glhf.OneMinusSrcAlpha) case pixel.ComposeDstOver: glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.One) case pixel.ComposeDstIn: glhf.BlendFunc(glhf.Zero, glhf.SrcAlpha) case pixel.ComposeDstOut: glhf.BlendFunc(glhf.Zero, glhf.OneMinusSrcAlpha) case pixel.ComposeDstAtop: glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.SrcAlpha) case pixel.ComposeXor: glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.OneMinusSrcAlpha) default: panic(errors.New("Canvas: invalid compose method")) } } // Clear fills the whole Canvas with a single color. func (c *Canvas) Clear(color color.Color) { c.gf.Dirty() rgba := pixel.ToRGBA(color) // color masking rgba = rgba.Mul(pixel.RGBA{ R: float64(c.col[0]), G: float64(c.col[1]), B: float64(c.col[2]), A: float64(c.col[3]), }) mainthread.CallNonBlock(func() { c.setGlhfBounds() c.gf.Frame().Begin() glhf.Clear( float32(rgba.R), float32(rgba.G), float32(rgba.B), float32(rgba.A), ) c.gf.Frame().End() }) } // Color returns the color of the pixel over the given position inside the Canvas. func (c *Canvas) Color(at pixel.Vec) pixel.RGBA { return c.gf.Color(at) } // Texture returns the underlying OpenGL Texture of this Canvas. // // Implements GLPicture interface. func (c *Canvas) Texture() *glhf.Texture { return c.gf.Texture() } type canvasTriangles struct { *GLTriangles dst *Canvas } func (ct *canvasTriangles) draw(tex *glhf.Texture, bounds pixel.Rect) { ct.dst.gf.Dirty() // save the current state vars to avoid race condition cmp := ct.dst.cmp mat := ct.dst.mat col := ct.dst.col smt := ct.dst.smooth mainthread.CallNonBlock(func() { ct.dst.setGlhfBounds() setBlendFunc(cmp) frame := ct.dst.gf.Frame() shader := ct.dst.shader frame.Begin() shader.Begin() dstBounds := ct.dst.Bounds() shader.SetUniformAttr(canvasBounds, mgl32.Vec4{ float32(dstBounds.Min.X()), float32(dstBounds.Min.Y()), float32(dstBounds.W()), float32(dstBounds.H()), }) shader.SetUniformAttr(canvasTransform, mat) shader.SetUniformAttr(canvasColorMask, col) if tex == nil { ct.vs.Begin() ct.vs.Draw() ct.vs.End() } else { tex.Begin() bx, by, bw, bh := intBounds(bounds) shader.SetUniformAttr(canvasTexBounds, mgl32.Vec4{ float32(bx), float32(by), float32(bw), float32(bh), }) if tex.Smooth() != smt { tex.SetSmooth(smt) } ct.vs.Begin() ct.vs.Draw() ct.vs.End() tex.End() } shader.End() frame.End() }) } func (ct *canvasTriangles) Draw() { ct.draw(nil, pixel.Rect{}) } type canvasPicture struct { GLPicture dst *Canvas } func (cp *canvasPicture) Draw(t pixel.TargetTriangles) { ct := t.(*canvasTriangles) if cp.dst != ct.dst { panic(fmt.Errorf("(%T).Draw: TargetTriangles generated by different Canvas", cp)) } ct.draw(cp.GLPicture.Texture(), cp.GLPicture.Bounds()) } const ( canvasPosition int = iota canvasColor canvasTexture canvasIntensity ) var canvasVertexFormat = glhf.AttrFormat{ canvasPosition: {Name: "position", Type: glhf.Vec2}, canvasColor: {Name: "color", Type: glhf.Vec4}, canvasTexture: {Name: "texture", Type: glhf.Vec2}, canvasIntensity: {Name: "intensity", Type: glhf.Float}, } const ( canvasTransform int = iota canvasColorMask canvasBounds canvasTexBounds ) var canvasUniformFormat = glhf.AttrFormat{ canvasTransform: {Name: "transform", Type: glhf.Mat3}, canvasColorMask: {Name: "colorMask", Type: glhf.Vec4}, canvasBounds: {Name: "bounds", Type: glhf.Vec4}, canvasTexBounds: {Name: "texBounds", Type: glhf.Vec4}, } var canvasVertexShader = ` #version 330 core in vec2 position; in vec4 color; in vec2 texture; in float intensity; out vec4 Color; out vec2 Texture; out float Intensity; uniform mat3 transform; uniform vec4 bounds; void main() { vec2 transPos = (transform * vec3(position, 1.0)).xy; vec2 normPos = (transPos - bounds.xy) / (bounds.zw) * 2 - vec2(1, 1); gl_Position = vec4(normPos, 0.0, 1.0); Color = color; Texture = texture; Intensity = intensity; } ` var canvasFragmentShader = ` #version 330 core in vec4 Color; in vec2 Texture; in float Intensity; out vec4 color; uniform vec4 colorMask; uniform vec4 texBounds; uniform sampler2D tex; void main() { if (Intensity == 0) { color = colorMask * Color; } else { color = vec4(0, 0, 0, 0); color += (1 - Intensity) * Color; vec2 t = (Texture - texBounds.xy) / texBounds.zw; color += Intensity * Color * texture(tex, t); color *= colorMask; } } `