Revert "internal/graphics: change the definition of MaxVerticesCount"

This reverts commit 3047ad202a.

Reason: Failed to build for 32bit architectures

Updates #2612

image.go

@@ -438,6 +438,9 @@ func (i *Image) DrawTriangles(vertices []Vertex, indices []uint16, img *Image, o
 		if int(idx) >= len(vertices) {
 			panic(fmt.Sprintf("ebiten: indices[%d] must be less than len(vertices) (%d) but was %d", i, len(vertices), idx))
 		}
+		if idx >= MaxVerticesCount {
+			panic(fmt.Sprintf("ebiten: indices[%d] must be less than MaxVerticesCount %d but was %d", i, MaxVerticesCount, idx))
+		}
 	}
 
 	if options == nil {
@@ -600,6 +603,9 @@ func (i *Image) DrawTrianglesShader(vertices []Vertex, indices []uint16, shader
 		if int(idx) >= len(vertices) {
 			panic(fmt.Sprintf("ebiten: indices[%d] must be less than len(vertices) (%d) but was %d", i, len(vertices), idx))
 		}
+		if idx >= MaxVerticesCount {
+			panic(fmt.Sprintf("ebiten: indices[%d] must be less than MaxVerticesCount %d but was %d", i, MaxVerticesCount, idx))
+		}
 	}
 
 	if options == nil {

image_test.go

@@ -2805,7 +2805,7 @@ func BenchmarkColorMScale(b *testing.B) {
 	}
 }
 
-func TestImageMoreIndicesThanMaxUint16(t *testing.T) {
+func TestIndicesOverflow(t *testing.T) {
 	const (
 		w = 16
 		h = 16
@@ -2817,10 +2817,10 @@ func TestImageMoreIndicesThanMaxUint16(t *testing.T) {
 
 	op := &ebiten.DrawTrianglesOptions{}
 	vs := make([]ebiten.Vertex, 3)
-	is := make([]uint16, 65538)
+	is := make([]uint16, graphics.MaxVerticesCount/3*3)
 	dst.DrawTriangles(vs, is, src, op)
 
-	// The next draw call should work well (and this is likely batched).
+	// Cause an overflow for indices.
 	vs = []ebiten.Vertex{
 		{
 			DstX:   0,
@@ -2877,7 +2877,7 @@ func TestImageMoreIndicesThanMaxUint16(t *testing.T) {
 	}
 }
 
-func TestImageMoreVerticesThanMaxUint16(t *testing.T) {
+func TestVerticesOverflow(t *testing.T) {
 	const (
 		w = 16
 		h = 16
@@ -2888,11 +2888,11 @@ func TestImageMoreVerticesThanMaxUint16(t *testing.T) {
 	src.Fill(color.White)
 
 	op := &ebiten.DrawTrianglesOptions{}
-	vs := make([]ebiten.Vertex, math.MaxUint16+1)
+	vs := make([]ebiten.Vertex, graphics.MaxVerticesCount-1)
 	is := make([]uint16, 3)
 	dst.DrawTriangles(vs, is, src, op)
 
-	// The next draw call should work well (and this is likely batched).
+	// Cause an overflow for vertices.
 	vs = []ebiten.Vertex{
 		{
 			DstX:   0,
@@ -2949,6 +2949,26 @@ func TestImageMoreVerticesThanMaxUint16(t *testing.T) {
 	}
 }
 
+func TestTooManyVertices(t *testing.T) {
+	const (
+		w = 16
+		h = 16
+	)
+
+	dst := ebiten.NewImage(w, h)
+	src := ebiten.NewImage(w, h)
+	src.Fill(color.White)
+
+	op := &ebiten.DrawTrianglesOptions{}
+	vs := make([]ebiten.Vertex, graphics.MaxVerticesCount+1)
+	is := make([]uint16, 3)
+	dst.DrawTriangles(vs, is, src, op)
+
+	// Force to cause flushing the graphics commands.
+	// Confirm this doesn't freeze.
+	dst.At(0, 0)
+}
+
 func TestImageNewImageFromEbitenImage(t *testing.T) {
 	const (
 		w = 16
@@ -4298,6 +4318,48 @@ func TestImageDrawTrianglesShaderWithGreaterIndexThanVerticesCount(t *testing.T)
 	dst.DrawTrianglesShader(vs, is, shader, nil)
 }
 
+// Issue #2611
+func TestImageDrawTrianglesWithTooBigIndex(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("DrawTriangles must panic but not")
+		}
+	}()
+
+	const w, h = 16, 16
+	dst := ebiten.NewImage(w, h)
+	src := ebiten.NewImage(w, h)
+
+	vs := make([]ebiten.Vertex, ebiten.MaxVerticesCount+1)
+	is := []uint16{0, 1, 2, 1, 2, ebiten.MaxVerticesCount}
+	dst.DrawTriangles(vs, is, src, nil)
+}
+
+// Issue #2611
+func TestImageDrawTrianglesShaderWithTooBigIndex(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("DrawTrianglesShader must panic but not")
+		}
+	}()
+
+	const w, h = 16, 16
+	dst := ebiten.NewImage(w, h)
+
+	vs := make([]ebiten.Vertex, ebiten.MaxVerticesCount+1)
+	is := []uint16{0, 1, 2, 1, 2, ebiten.MaxVerticesCount}
+	shader, err := ebiten.NewShader([]byte(`
+		package main
+		func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
+			return color
+		}
+	`))
+	if err != nil {
+		t.Fatalf("could not compile shader: %v", err)
+	}
+	dst.DrawTrianglesShader(vs, is, shader, nil)
+}
+
 // Issue #2733
 func TestImageGeoMAfterDraw(t *testing.T) {
 	src := ebiten.NewImage(1, 1)

internal/graphics/vertex.go

@@ -46,10 +46,12 @@ const (
 	VertexFloatCount = 8
 
 	// MaxVerticesCount is the maximum number of vertices for one draw call.
-	// This value is 2^32 - 1, as the index type is uint32.
+	// This value is 2^16 - 1 = 65535, as the index type is uint16.
-	// This value cannot be exactly 2^32 especially with WebGL 2, as 2^32th vertex is not rendered correctly.
+	// This value cannot be exactly 2^16 == 65536 especially with WebGL 2, as 65536th vertex is not rendered correctly.
 	// See https://registry.khronos.org/webgl/specs/latest/2.0/#5.18 .
-	MaxVerticesCount     = math.MaxUint32
+	//
+	// TODO: Use MaxUint32 and move these values to internal/graphicscommand (#2612)
+	MaxVerticesCount     = math.MaxUint16
 	MaxVertexFloatsCount = MaxVerticesCount * VertexFloatCount
 )
 

internal/ui/image.go

@@ -139,7 +139,8 @@ func (i *Image) WritePixels(pix []byte, region image.Rectangle) {
 		copy(clr[:], pix)
 		i.dotsBuffer[region.Min] = clr
 
-		if len(i.dotsBuffer) >= 10000 {
+		// One square requires 6 indices (= 2 triangles).
+		if len(i.dotsBuffer) >= graphics.MaxVerticesCount/6 {
 			i.flushDotsBufferIfNeeded()
 		}
 		return