fixed a race condition causing unstable polygons

.gitignore

@@ -1,2 +1,3 @@
 test
 .vscode
+*.exe

examples/shaders/simple/main.go

@@ -0,0 +1,98 @@
+package main
+
+import (
+	"image"
+	"os"
+	"time"
+
+	_ "image/png"
+
+	"github.com/faiface/pixel"
+	"github.com/faiface/pixel/pixelgl"
+	"golang.org/x/image/colornames"
+)
+
+func loadPicture(path string) (pixel.Picture, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+	img, _, err := image.Decode(file)
+	if err != nil {
+		return nil, err
+	}
+	return pixel.PictureDataFromImage(img), nil
+}
+
+func run() {
+	cfg := pixelgl.WindowConfig{
+		Title:  "Pixel Rocks!",
+		Bounds: pixel.R(0, 0, 1024, 768),
+		VSync:  true,
+	}
+	win, err := pixelgl.NewWindow(cfg)
+	if err != nil {
+		panic(err)
+	}
+
+	pic, err := loadPicture("thegopherproject.png")
+	if err != nil {
+		panic(err)
+	}
+
+	start := time.Now()
+	var utime float32
+
+	sprite := pixel.NewSprite(pic, pic.Bounds())
+	sc := pixelgl.NewCanvas(win.Bounds())
+	sc.SetFragmentShader(customFragShader)
+	sc.BindUniform("u_time", &utime)
+	sc.RecompileShader()
+
+	sprite.Draw(sc, pixel.IM.Moved(win.Bounds().Center()))
+	win.Clear(colornames.Greenyellow)
+
+	for !win.Closed() {
+		utime = float32(time.Since(start).Seconds())
+		sprite.Draw(sc, pixel.IM.Moved(win.Bounds().Center()))
+		sc.Draw(win, pixel.IM.Moved(win.Bounds().Center()))
+		win.Update()
+	}
+}
+
+func main() {
+	pixelgl.Run(run)
+}
+
+var customFragShader = `
+#version 330 core
+
+in vec4 Color;
+in vec2 TexCoords;
+in float Intensity;
+
+out vec4 color;
+
+uniform vec4 colorMask;
+uniform vec4 texBounds;
+uniform sampler2D tex;
+uniform float u_time;
+
+void main() {
+	if (Intensity == 0) {
+		color = colorMask * Color;
+	} else {
+		color = vec4(0, 0, 0, 0);
+		color += (1 - Intensity) * Color;
+		vec2 t = (TexCoords - texBounds.xy) / texBounds.zw;
+		color += Intensity * Color * texture(tex, t);
+		color *= colorMask;
+	}
+	color.rgb *= cos(u_time*5);
+}
+`
+
+// var umouse = mgl32.Vec2{}
+// umouse[0] = float32(win.MousePosition().X) / 1024
+// umouse[1] = float32(win.MousePosition().Y) / 768

examples/shaders/waterreflection/main.go

@@ -0,0 +1,153 @@
+package main
+
+import (
+	"image"
+	"math"
+	"os"
+	"time"
+
+	"golang.org/x/image/colornames"
+
+	_ "image/png"
+
+	"github.com/faiface/pixel"
+	"github.com/faiface/pixel/imdraw"
+	"github.com/faiface/pixel/pixelgl"
+)
+
+func loadPicture(path string) (pixel.Picture, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+	img, _, err := image.Decode(file)
+	if err != nil {
+		return nil, err
+	}
+	return pixel.PictureDataFromImage(img), nil
+}
+
+func run() {
+
+	cfg := pixelgl.WindowConfig{
+		Title:  "Pixel Rocks!",
+		Bounds: pixel.R(0, 0, 1024, 768),
+		VSync:  true,
+	}
+	pic, err := loadPicture("thegopherproject.png")
+	if err != nil {
+		panic(err)
+	}
+	win, err := pixelgl.NewWindow(cfg)
+	if err != nil {
+		panic(err)
+	}
+
+	start := time.Now()
+	var utime float32
+
+	sprite := pixel.NewSprite(pic, pic.Bounds())
+
+	bounds := pic.Bounds()
+
+	sc := pixelgl.NewCanvas(pic.Bounds())
+
+	sc2 := pixelgl.NewCanvas(pic.Bounds())
+	sc2.SetFragmentShader(reflectionShader)
+	sc2.BindUniform("u_time", &utime)
+	sc2.RecompileShader()
+	imd := imdraw.New(nil)
+	imd.Color = colornames.Blueviolet
+	imd.EndShape = imdraw.RoundEndShape
+
+	curpos := pixel.V(sc.Bounds().Center().X, -25)
+	tgtpos := pixel.V(sc.Bounds().Center().X, 316)
+	last := start
+
+	for !win.Closed() {
+
+		dt := time.Since(last).Seconds()
+		last = time.Now()
+		curpos = pixel.Lerp(curpos, tgtpos, 1-math.Pow(1.0/16, dt*0.5))
+		sc.Clear(colornames.Black)
+		sc2.Clear(colornames.Black)
+		win.Clear(colornames.Black)
+		imd.Clear()
+		imd.Push(pixel.V(0, 0), pixel.V(bounds.Max.X, 0))
+		imd.Push(pixel.V(bounds.Max.X, 0), pixel.V(bounds.Max.X, bounds.Max.Y))
+		imd.Push(pixel.V(bounds.Max.X, bounds.Max.Y), pixel.V(0, bounds.Max.Y))
+		imd.Push(pixel.V(0, bounds.Max.Y), pixel.V(0, 0))
+		imd.Line(3)
+
+		utime = float32(time.Since(start).Seconds())
+		sprite.Draw(sc, pixel.IM.Moved(curpos))
+		sc.Draw(sc2, pixel.IM.Moved(sc2.Bounds().Center()))
+
+		imd.Draw(sc2)
+		sc2.Draw(win, pixel.IM.Moved(win.Bounds().Center()))
+
+		win.Update()
+	}
+}
+
+func main() {
+	pixelgl.Run(run)
+}
+
+var reflectionShader = `
+#version 330 core
+
+in vec4 Color;
+in vec2 TexCoords;
+in float Intensity;
+
+out vec4 color;
+
+uniform vec4 colorMask;
+uniform vec4 texBounds;
+uniform sampler2D tex;
+uniform float u_time;
+
+void main() {
+	if (Intensity == 0) {
+		color = colorMask * Color;
+	} else {
+		color = vec4(0, 0, 0, 0);
+		color += (1 - Intensity) * Color;
+		vec2 t = (TexCoords - texBounds.xy) / texBounds.zw;
+		color += Intensity * Color * texture(tex, t);
+		color *= colorMask;
+		vec2 uv =  t;
+		vec3 overlayColor = vec3(0.1,0.1,1);
+		float sepoffset = 0.005*cos(u_time*3.0);
+		
+		if (t.y < 0.3 + sepoffset)
+		{
+			float xoffset = 0.005*cos(u_time*3.0+200.0*t.y);
+			float yoffset = ((0.3 - t.y)/0.3) * 0.05*(1.0+cos(u_time*3.0+50.0*t.y));
+			color = texture(tex, vec2(t.x+xoffset,t.y+yoffset));
+		}
+	}
+}
+`
+
+// void main() {
+// 	fragColor = vec4(0, 0, 0, 0);
+// 	fragColor += (1 - Intensity) * incolor;
+// 	vec2 t = (TexCoords) / texBounds.zw;
+// 	fragColor += Intensity * incolor * texture(tex, t);
+// 	fragColor *= colorMask;
+
+// 	vec2 uv =  t;
+// 	vec3 overlayColor = vec3(0.1,0.1,1);
+// 	float sepoffset = 0.005*cos(u_time*3.0);
+
+// 	if (t.y < 0.3 + sepoffset)
+// 	{
+//         float xoffset = 0.005*cos(u_time*3.0+200.0*t.y);
+// 		float yoffset = ((0.3 - t.y)/0.3) * 0.05*(1.0+cos(u_time*3.0+50.0*t.y));
+//         fragColor = texture(tex, vec2(t.x+xoffset,t.y+yoffset));
+// 	}
+// }
+// `

pixelgl/canvas.go

@@ -17,7 +17,7 @@ import (
 // It supports TrianglesPosition, TrianglesColor, TrianglesPicture and PictureColor.
 type Canvas struct {
 	gf     *GLFrame
-	shader *glhf.Shader
+	shader *GLShader
 
 	cmp    pixel.ComposeMethod
 	mat    mgl32.Mat3
@@ -37,23 +37,9 @@ func NewCanvas(bounds pixel.Rect) *Canvas {
 		col: mgl32.Vec4{1, 1, 1, 1},
 	}
 
+	baseShader(c)
 	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
-
+	c.shader.compile()
 	return c
 }
 
@@ -62,7 +48,7 @@ func NewCanvas(bounds pixel.Rect) *Canvas {
 // TrianglesPosition, TrianglesColor and TrianglesPicture are supported.
 func (c *Canvas) MakeTriangles(t pixel.Triangles) pixel.TargetTriangles {
 	return &canvasTriangles{
-		GLTriangles: NewGLTriangles(c.shader, t),
+		GLTriangles: NewGLTriangles(c.shader.s, t),
 		dst:         c,
 	}
 }
@@ -279,29 +265,33 @@ func (ct *canvasTriangles) draw(tex *glhf.Texture, bounds pixel.Rect) {
 
 	// save the current state vars to avoid race condition
 	cmp := ct.dst.cmp
+	smt := ct.dst.smooth
 	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
+		shader := ct.dst.shader.s
 
 		frame.Begin()
 		shader.Begin()
 
+		ct.dst.shader.uniformDefaults.transform = mat
+		ct.dst.shader.uniformDefaults.colormask = col
 		dstBounds := ct.dst.Bounds()
-		shader.SetUniformAttr(canvasBounds, mgl32.Vec4{
+		ct.dst.shader.uniformDefaults.bounds = mgl32.Vec4{
 			float32(dstBounds.Min.X),
 			float32(dstBounds.Min.Y),
 			float32(dstBounds.W()),
 			float32(dstBounds.H()),
-		})
-		shader.SetUniformAttr(canvasTransform, mat)
-		shader.SetUniformAttr(canvasColorMask, col)
+		}
+
+		for loc, u := range ct.dst.shader.uniforms {
+			ct.dst.shader.s.SetUniformAttr(loc, u.Value)
+		}
 
 		if tex == nil {
 			ct.vs.Begin()
@@ -311,7 +301,7 @@ func (ct *canvasTriangles) draw(tex *glhf.Texture, bounds pixel.Rect) {
 			tex.Begin()
 
 			bx, by, bw, bh := intBounds(bounds)
-			shader.SetUniformAttr(canvasTexBounds, mgl32.Vec4{
+			shader.SetUniformAttr(canvasTexBounds, &mgl32.Vec4{
 				float32(bx),
 				float32(by),
 				float32(bw),
@@ -358,7 +348,7 @@ const (
 	canvasIntensity
 )
 
-var canvasVertexFormat = glhf.AttrFormat{
+var defaultCanvasVertexFormat = glhf.AttrFormat{
 	canvasPosition:  {Name: "position", Type: glhf.Vec2},
 	canvasColor:     {Name: "color", Type: glhf.Vec4},
 	canvasTexCoords: {Name: "texCoords", Type: glhf.Vec2},
@@ -379,53 +369,14 @@ var canvasUniformFormat = glhf.AttrFormat{
 	canvasTexBounds: {Name: "texBounds", Type: glhf.Vec4},
 }
 
-var canvasVertexShader = `
-#version 330 core
-
-in vec2 position;
-in vec4 color;
-in vec2 texCoords;
-in float intensity;
-
-out vec4 Color;
-out vec2 TexCoords;
-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;
-	TexCoords = texCoords;
-	Intensity = intensity;
+func (c *Canvas) BindUniform(Name string, Value interface{}) {
+	c.shader.AddUniform(Name, Value)
 }
-`
 
-var canvasFragmentShader = `
-#version 330 core
-
-in vec4 Color;
-in vec2 TexCoords;
-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 = (TexCoords - texBounds.xy) / texBounds.zw;
-		color += Intensity * Color * texture(tex, t);
-		color *= colorMask;
-	}
+func (c *Canvas) RecompileShader() {
+	c.shader.compile()
+}
+
+func (c *Canvas) SetFragmentShader(fs string) {
+	c.shader.fs = fs
 }
-`

pixelgl/shader.go

@@ -0,0 +1,262 @@
+package pixelgl
+
+import (
+	"fmt"
+
+	"github.com/faiface/glhf"
+	"github.com/faiface/mainthread"
+	"github.com/faiface/pixel"
+	"github.com/go-gl/mathgl/mgl32"
+	"github.com/pkg/errors"
+)
+
+type (
+	GLShader struct {
+		s      *glhf.Shader
+		vf, uf glhf.AttrFormat
+		vs, fs string
+
+		uniforms []gsUniformAttr
+
+		uniformDefaults struct {
+			transform mgl32.Mat3
+			colormask mgl32.Vec4
+			bounds    mgl32.Vec4
+			texbounds mgl32.Vec4
+		}
+	}
+
+	gsUniformAttr struct {
+		Name  string
+		Type  AttrType
+		Value interface{}
+	}
+)
+
+func (gs *GLShader) compile() {
+	gs.uf = nil
+	for _, u := range gs.uniforms {
+		gs.uf = append(gs.uf, glhf.Attr{
+			Name: u.Name,
+			Type: glhf.AttrType(u.Type),
+		})
+	}
+	var shader *glhf.Shader
+	mainthread.Call(func() {
+		var err error
+		shader, err = glhf.NewShader(
+			gs.vf,
+			gs.uf,
+			gs.vs,
+			gs.fs,
+		)
+		if err != nil {
+			panic(errors.Wrap(err, "failed to create Canvas, there's a bug in the shader"))
+		}
+	})
+
+	gs.s = shader
+}
+func (gs *GLShader) GetUniform(Name string) int {
+	for i, u := range gs.uniforms {
+		if u.Name == Name {
+			return i
+		}
+	}
+	return -1
+}
+func (gs *GLShader) AddUniform(Name string, Value interface{}) {
+	Type := getUniformType(Value)
+	fmt.Println(Type)
+	if loc := gs.GetUniform(Name); loc > -1 {
+		gs.uniforms[loc].Name = Name
+		gs.uniforms[loc].Type = Type
+		gs.uniforms[loc].Value = Value
+		return
+	}
+	gs.uniforms = append(gs.uniforms, gsUniformAttr{
+		Name:  Name,
+		Type:  Type,
+		Value: Value,
+	})
+}
+
+func (c *Canvas) setUniforms(texbounds pixel.Rect) {
+	mat := c.mat
+	col := c.col
+	c.shader.uniformDefaults.transform = mat
+	c.shader.uniformDefaults.colormask = col
+	dstBounds := c.Bounds()
+	c.shader.uniformDefaults.bounds = mgl32.Vec4{
+		float32(dstBounds.Min.X),
+		float32(dstBounds.Min.Y),
+		float32(dstBounds.W()),
+		float32(dstBounds.H()),
+	}
+
+	for loc, u := range c.shader.uniforms {
+		c.shader.s.SetUniformAttr(loc, u.Value)
+	}
+}
+
+func baseShader(c *Canvas) {
+	gs := &GLShader{
+		vf: defaultCanvasVertexFormat,
+		vs: defaultCanvasVertexShader,
+		fs: baseCanvasFragmentShader,
+	}
+
+	gs.AddUniform("transform", &gs.uniformDefaults.transform)
+	gs.AddUniform("colorMask", &gs.uniformDefaults.colormask)
+	gs.AddUniform("bounds", &gs.uniformDefaults.bounds)
+	gs.AddUniform("texBounds", &gs.uniformDefaults.texbounds)
+
+	c.shader = gs
+}
+func getUniformType(v interface{}) AttrType {
+	switch v.(type) {
+	case int32:
+		return Int
+	case float32:
+		return Float
+	case mgl32.Vec2:
+		return Vec2
+	case mgl32.Vec3:
+		return Vec3
+	case mgl32.Vec4:
+		return Vec4
+	case mgl32.Mat2:
+		return Mat2
+	case mgl32.Mat2x3:
+		return Mat23
+	case mgl32.Mat2x4:
+		return Mat24
+	case mgl32.Mat3:
+		return Mat3
+	case mgl32.Mat3x2:
+		return Mat32
+	case mgl32.Mat3x4:
+		return Mat34
+	case mgl32.Mat4:
+		return Mat4
+	case mgl32.Mat4x2:
+		return Mat42
+	case mgl32.Mat4x3:
+		return Mat43
+	case *mgl32.Vec2:
+		return Vec2p
+	case *mgl32.Vec3:
+		return Vec3p
+	case *mgl32.Vec4:
+		return Vec4p
+	case *mgl32.Mat2:
+		return Mat2p
+	case *mgl32.Mat2x3:
+		return Mat23p
+	case *mgl32.Mat2x4:
+		return Mat24p
+	case *mgl32.Mat3:
+		return Mat3p
+	case *mgl32.Mat3x2:
+		return Mat32p
+	case *mgl32.Mat3x4:
+		return Mat34p
+	case *mgl32.Mat4:
+		return Mat4p
+	case *mgl32.Mat4x2:
+		return Mat42p
+	case *mgl32.Mat4x3:
+		return Mat43p
+	case *int32:
+		return Intp
+	case *float32:
+		return Floatp
+	default:
+		panic("invalid AttrType")
+	}
+}
+
+type AttrType int
+
+// List of all possible attribute types.
+const (
+	Int AttrType = iota
+	Float
+	Vec2
+	Vec3
+	Vec4
+	Mat2
+	Mat23
+	Mat24
+	Mat3
+	Mat32
+	Mat34
+	Mat4
+	Mat42
+	Mat43
+	Intp
+	Floatp
+	Vec2p
+	Vec3p
+	Vec4p
+	Mat2p
+	Mat23p
+	Mat24p
+	Mat3p
+	Mat32p
+	Mat34p
+	Mat4p
+	Mat42p
+	Mat43p
+)
+
+var defaultCanvasVertexShader = `
+#version 330 core
+
+in vec2 position;
+in vec4 color;
+in vec2 texCoords;
+in float intensity;
+
+out vec4 Color;
+out vec2 TexCoords;
+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;
+	TexCoords = texCoords;
+	Intensity = intensity;
+}
+`
+
+var baseCanvasFragmentShader = `
+#version 330 core
+
+in vec4 Color;
+in vec2 TexCoords;
+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 = (TexCoords - texBounds.xy) / texBounds.zw;
+		color += Intensity * Color * texture(tex, t);
+		color *= colorMask;
+	}
+}
+`