vector: allow NonZero for AppendVerticesAndIndicesForStroke

Closes #2833

doc.go

@@ -81,6 +81,7 @@
 //
 //	"debug":                      Use a debug layer.
 //	"warp":                       Use WARP (i.e. software rendering).
+//	"tearing":                    Allow tearing when vsync is off.
 //	"version=VERSION":            Specify a DirectX version (e.g. 11).
 //	"featurelevel=FEATURE_LEVEL": Specify a feature level (e.g. 11_0). This is for DirectX 12.
 //

examples/shader/lighting.go

@@ -14,14 +14,19 @@
 
 //go:build ignore
 
+// Specify the 'pixel' mode.
 //kage:unit pixels
 
 package main
 
+// Uniform variables.
 var Time float
 var Cursor vec2
 
+// Fragment is the entry point of the fragment shader.
+// Fragment returns the color value for the current position.
 func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
+	// You can define variables with a short variable declaration like Go.
 	pos := dstPos.xy - imageDstOrigin()
 
 	lightpos := vec3(Cursor, 50)
@@ -29,5 +34,8 @@ func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
 	normal := normalize(imageSrc1UnsafeAt(srcPos) - 0.5)
 	const ambient = 0.25
 	diffuse := 0.75 * max(0.0, dot(normal.xyz, lightdir))
+
+	// You can treat multiple source images by
+	// imageSrc[N]At or imageSrc[N]UnsafeAt.
 	return imageSrc0UnsafeAt(srcPos) * (ambient + diffuse)
 }

examples/vector/main.go

@@ -140,12 +140,16 @@ func drawEbitenText(screen *ebiten.Image, x, y int, aa bool, line bool) {
 
 	op := &ebiten.DrawTrianglesOptions{}
 	op.AntiAlias = aa
-	if !line {
-		// ebiten.EvenOdd is also fine here.
-		// NonZero and EvenOdd differ when rendering a complex polygons with self-intersections and/or holes.
-		// See https://en.wikipedia.org/wiki/Nonzero-rule and https://en.wikipedia.org/wiki/Even%E2%80%93odd_rule .
-		op.FillRule = ebiten.NonZero
-	}
+
+	// For strokes (AppendVerticesAndIndicesForStroke), FillAll and NonZero work.
+	//
+	// For filling (AppendVerticesAndIndicesForFilling), NonZero and EvenOdd work.
+	// NonZero and EvenOdd differ when rendering a complex polygons with self-intersections and/or holes.
+	// See https://en.wikipedia.org/wiki/Nonzero-rule and https://en.wikipedia.org/wiki/Even%E2%80%93odd_rule .
+	//
+	// For simplicity, this example always uses NonZero, whichever strokes or filling is done.
+	op.FillRule = ebiten.NonZero
+
 	screen.DrawTriangles(vs, is, whiteSubImage, op)
 }
 
@@ -199,9 +203,7 @@ func drawEbitenLogo(screen *ebiten.Image, x, y int, aa bool, line bool) {
 
 	op := &ebiten.DrawTrianglesOptions{}
 	op.AntiAlias = aa
-	if !line {
-		op.FillRule = ebiten.NonZero
-	}
+	op.FillRule = ebiten.NonZero
 	screen.DrawTriangles(vs, is, whiteSubImage, op)
 }
 
@@ -243,9 +245,7 @@ func drawArc(screen *ebiten.Image, count int, aa bool, line bool) {
 
 	op := &ebiten.DrawTrianglesOptions{}
 	op.AntiAlias = aa
-	if !line {
-		op.FillRule = ebiten.NonZero
-	}
+	op.FillRule = ebiten.NonZero
 	screen.DrawTriangles(vs, is, whiteSubImage, op)
 }
 
@@ -300,9 +300,7 @@ func drawWave(screen *ebiten.Image, counter int, aa bool, line bool) {
 
 	op := &ebiten.DrawTrianglesOptions{}
 	op.AntiAlias = aa
-	if !line {
-		op.FillRule = ebiten.NonZero
-	}
+	op.FillRule = ebiten.NonZero
 	screen.DrawTriangles(vs, is, whiteSubImage, op)
 }
 

internal/graphicsdriver/directx/graphics11_windows.go

@@ -153,7 +153,7 @@ type graphics11 struct {
 	newScreenHeight int
 }
 
-func newGraphics11(useWARP bool, useDebugLayer bool) (gr11 *graphics11, ferr error) {
+func newGraphics11(useWARP bool, useDebugLayer bool, allowTearing bool) (gr11 *graphics11, ferr error) {
 	g := &graphics11{
 		vsyncEnabled: true,
 	}
@@ -207,7 +207,7 @@ func newGraphics11(useWARP bool, useDebugLayer bool) (gr11 *graphics11, ferr err
 	}
 	dxgiFactory := (*_IDXGIFactory)(df)
 
-	gi, err := newGraphicsInfra(dxgiFactory)
+	gi, err := newGraphicsInfra(dxgiFactory, allowTearing)
 	if err != nil {
 		return nil, err
 	}

internal/graphicsdriver/directx/graphics12_windows.go

@@ -106,7 +106,7 @@ type graphics12 struct {
 	pipelineStates
 }
 
-func newGraphics12(useWARP bool, useDebugLayer bool, featureLevel _D3D_FEATURE_LEVEL) (*graphics12, error) {
+func newGraphics12(useWARP bool, useDebugLayer bool, allowTearing bool, featureLevel _D3D_FEATURE_LEVEL) (*graphics12, error) {
 	g := &graphics12{}
 
 	// Initialize not only a device but also other members like a fence.
@@ -116,7 +116,7 @@ func newGraphics12(useWARP bool, useDebugLayer bool, featureLevel _D3D_FEATURE_L
 			return nil, err
 		}
 	} else {
-		if err := g.initializeDesktop(useWARP, useDebugLayer, featureLevel); err != nil {
+		if err := g.initializeDesktop(useWARP, useDebugLayer, allowTearing, featureLevel); err != nil {
 			return nil, err
 		}
 	}
@@ -124,7 +124,7 @@ func newGraphics12(useWARP bool, useDebugLayer bool, featureLevel _D3D_FEATURE_L
 	return g, nil
 }
 
-func (g *graphics12) initializeDesktop(useWARP bool, useDebugLayer bool, featureLevel _D3D_FEATURE_LEVEL) (ferr error) {
+func (g *graphics12) initializeDesktop(useWARP bool, useDebugLayer bool, allowTearing bool, featureLevel _D3D_FEATURE_LEVEL) (ferr error) {
 	if err := d3d12.Load(); err != nil {
 		return err
 	}
@@ -152,7 +152,7 @@ func (g *graphics12) initializeDesktop(useWARP bool, useDebugLayer bool, feature
 	if err != nil {
 		return err
 	}
-	gi, err := newGraphicsInfra(f)
+	gi, err := newGraphicsInfra(f, allowTearing)
 	if err != nil {
 		return err
 	}

internal/graphicsdriver/directx/graphics_windows.go

@@ -81,6 +81,7 @@ func NewGraphics() (graphicsdriver.Graphics, error) {
 
 	var useWARP bool
 	var useDebugLayer bool
+	var allowTearing bool
 	version := 11
 
 	// Specify the feature level 11 by default.
@@ -108,6 +109,8 @@ func NewGraphics() (graphicsdriver.Graphics, error) {
 			useWARP = true
 		case t == "debug":
 			useDebugLayer = true
+		case t == "tearing":
+			allowTearing = true
 		case strings.HasPrefix(t, "version="):
 			v, err := strconv.Atoi(t[len("version="):])
 			if err != nil {
@@ -130,13 +133,13 @@ func NewGraphics() (graphicsdriver.Graphics, error) {
 
 	switch version {
 	case 11:
-		g, err := newGraphics11(useWARP, useDebugLayer)
+		g, err := newGraphics11(useWARP, useDebugLayer, allowTearing)
 		if err != nil {
 			return nil, err
 		}
 		return g, nil
 	case 12:
-		g, err := newGraphics12(useWARP, useDebugLayer, featureLevel)
+		g, err := newGraphics12(useWARP, useDebugLayer, allowTearing, featureLevel)
 		if err != nil {
 			return nil, err
 		}
@@ -163,19 +166,21 @@ type graphicsInfra struct {
 }
 
 // newGraphicsInfra takes the ownership of the given factory.
-func newGraphicsInfra(factory *_IDXGIFactory) (*graphicsInfra, error) {
+func newGraphicsInfra(factory *_IDXGIFactory, allowTearing bool) (*graphicsInfra, error) {
 	g := &graphicsInfra{
 		factory: factory,
 	}
 	runtime.SetFinalizer(g, (*graphicsInfra).release)
 
-	if f, err := g.factory.QueryInterface(&_IID_IDXGIFactory5); err == nil && f != nil {
-		factory := (*_IDXGIFactory5)(f)
-		defer factory.Release()
+	if allowTearing {
+		if f, err := g.factory.QueryInterface(&_IID_IDXGIFactory5); err == nil && f != nil {
+			factory := (*_IDXGIFactory5)(f)
+			defer factory.Release()
 
-		var allowTearing int32
-		if err := factory.CheckFeatureSupport(_DXGI_FEATURE_PRESENT_ALLOW_TEARING, unsafe.Pointer(&allowTearing), uint32(unsafe.Sizeof(allowTearing))); err == nil && allowTearing != 0 {
-			g.allowTearing = true
+			var allowTearing int32
+			if err := factory.CheckFeatureSupport(_DXGI_FEATURE_PRESENT_ALLOW_TEARING, unsafe.Pointer(&allowTearing), uint32(unsafe.Sizeof(allowTearing))); err == nil && allowTearing != 0 {
+				g.allowTearing = true
+			}
 		}
 	}
 

internal/shader/stmt.go

@@ -492,8 +492,8 @@ func (cs *compileState) assign(block *block, fname string, pos token.Pos, lhs, r
 	var rhsTypes []shaderir.Type
 	allblank := true
 
-	for i, e := range lhs {
-		if len(lhs) == len(rhs) {
+	if len(lhs) == len(rhs) {
+		for i, e := range lhs {
 			// Prase RHS first for the order of the statements.
 			r, rts, ss, ok := cs.parseExpr(block, fname, rhs[i], true)
 			if !ok {
@@ -582,6 +582,12 @@ func (cs *compileState) assign(block *block, fname string, pos token.Pos, lhs, r
 					cs.addError(pos, fmt.Sprintf("cannot use type %s as type %s in variable declaration", rts[i].String(), lts[i].String()))
 					return nil, false
 				}
+				switch lts[0].Main {
+				case shaderir.Int:
+					r[i].Const = gconstant.ToInt(r[i].Const)
+				case shaderir.Float:
+					r[i].Const = gconstant.ToFloat(r[i].Const)
+				}
 			}
 
 			if len(lhs) == 1 {
@@ -621,20 +627,21 @@ func (cs *compileState) assign(block *block, fname string, pos token.Pos, lhs, r
 						},
 					})
 			}
-		} else {
-			if i == 0 {
-				var ss []shaderir.Stmt
-				var ok bool
-				rhsExprs, rhsTypes, ss, ok = cs.parseExpr(block, fname, rhs[0], true)
-				if !ok {
-					return nil, false
-				}
-				if len(rhsExprs) != len(lhs) {
-					cs.addError(pos, "single-value context and multiple-value context cannot be mixed")
-				}
-				stmts = append(stmts, ss...)
-			}
+		}
+	} else {
+		var ss []shaderir.Stmt
+		var ok bool
+		rhsExprs, rhsTypes, ss, ok = cs.parseExpr(block, fname, rhs[0], true)
+		if !ok {
+			return nil, false
+		}
+		if len(lhs) != len(rhsExprs) {
+			cs.addError(pos, fmt.Sprintf("assignment mismatch: %d variables but %d", len(lhs), len(rhsExprs)))
+			return nil, false
+		}
+		stmts = append(stmts, ss...)
 
+		for i, e := range lhs {
 			if define {
 				if _, ok := e.(*ast.Ident); !ok {
 					cs.addError(pos, "non-name on the left side of :=")

internal/shader/syntax_test.go

@@ -4103,6 +4103,48 @@ func Bar() {
 `)); err != nil {
 		t.Error(err)
 	}
+
+	if _, err := compileToIR([]byte(`package main
+
+func Foo() {
+	a, b := 0
+	_, _ = a, b
+}
+`)); err == nil {
+		t.Error("compileToIR must return an error but did not")
+	}
+
+	if _, err := compileToIR([]byte(`package main
+
+func Foo() {
+	a, b, c := 0, 0
+	_, _ = a, b, c
+}
+`)); err == nil {
+		t.Error("compileToIR must return an error but did not")
+	}
+
+	if _, err := compileToIR([]byte(`package main
+
+func Foo() {
+	var a, b int
+	a, b = 0
+	_, _ = a, b
+}
+`)); err == nil {
+		t.Error("compileToIR must return an error but did not")
+	}
+
+	if _, err := compileToIR([]byte(`package main
+
+func Foo() {
+	var a, b, c int
+	a, b, c = 0, 0
+	_, _ = a, b, c
+}
+`)); err == nil {
+		t.Error("compileToIR must return an error but did not")
+	}
 }
 
 func TestSyntaxBitwiseOperator(t *testing.T) {

internal/shader/testdata/issue2655.expected.vs

@@ -5,7 +5,7 @@ void F2(in bool l0, out float l1, out vec2 l2);
 float F0(void) {
 	float l0 = float(0);
 	{
-		l0 = 0;
+		l0 = 0.0;
 	}
 	return l0;
 }
@@ -14,9 +14,9 @@ void F1(out float l0, out vec2 l1) {
 	float l2 = float(0);
 	vec2 l3 = vec2(0);
 	{
-		int l4 = 0;
+		float l4 = float(0);
 		vec2 l5 = vec2(0);
-		l4 = 0;
+		l4 = 0.0;
 		l2 = l4;
 		l5 = vec2(0.0);
 		l3 = l5;
@@ -30,9 +30,9 @@ void F2(in bool l0, out float l1, out vec2 l2) {
 	float l3 = float(0);
 	vec2 l4 = vec2(0);
 	{
-		int l5 = 0;
+		float l5 = float(0);
 		vec2 l6 = vec2(0);
-		l5 = 0;
+		l5 = 0.0;
 		l3 = l5;
 		l6 = vec2(0.0);
 		l4 = l6;

shader_test.go

@@ -2559,3 +2559,39 @@ func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
 		}
 	}
 }
+
+// Issue #2934
+func TestShaderAssignConst(t *testing.T) {
+	const w, h = 16, 16
+
+	dst := ebiten.NewImage(w, h)
+	s, err := ebiten.NewShader([]byte(`//kage:unit pixels
+
+package main
+
+func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
+	a := 0.0
+	a = 1
+	b, c := 0.0, 0.0
+	b, c = 1, 1
+	d := 0.0
+	d += 1
+	return vec4(a, b, c, d)
+}
+`))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dst.DrawRectShader(w, h, s, nil)
+
+	for j := 0; j < h; j++ {
+		for i := 0; i < w; i++ {
+			got := dst.At(i, j).(color.RGBA)
+			want := color.RGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff}
+			if !sameColors(got, want, 2) {
+				t.Errorf("dst.At(%d, %d): got: %v, want: %v", i, j, got, want)
+			}
+		}
+	}
+}

vector/path.go

@@ -480,7 +480,7 @@ type StrokeOptions struct {
 // The returned vertice's SrcX and SrcY are 0, and ColorR, ColorG, ColorB, and ColorA are 1.
 //
 // The returned values are intended to be passed to DrawTriangles or DrawTrianglesShader with a solid (non-transparent) color
-// with the FillAll fill rule (not NonZero or EvenOdd fill rule).
+// with FillAll or NonZero fill rule, not EvenOdd fill rule.
 func (p *Path) AppendVerticesAndIndicesForStroke(vertices []ebiten.Vertex, indices []uint16, op *StrokeOptions) ([]ebiten.Vertex, []uint16) {
 	if op == nil {
 		return vertices, indices
@@ -536,7 +536,8 @@ func (p *Path) AppendVerticesAndIndicesForStroke(vertices []ebiten.Vertex, indic
 					ColorA: 1,
 				})
 			}
-			indices = append(indices, idx, idx+1, idx+2, idx+1, idx+2, idx+3)
+			// All the triangles are rendered in clockwise order to enable NonZero filling rule (#2833).
+			indices = append(indices, idx, idx+1, idx+2, idx+1, idx+3, idx+2)
 
 			// Add line joints.
 			var nextRect [4]point