graphics: Use source-border check even at DrawTriangles

DrawTriangles can now take a sub-image.

image.go

@@ -411,6 +411,7 @@ type Vertex struct {
 	DstY float32
 
 	// SrcX and SrcY represents a point on a source image.
+	// Note that SrcX/SrcY on a sub-image should be in its bounds.
 	SrcX float32
 	SrcY float32
 
@@ -452,11 +453,6 @@ const MaxIndicesNum = graphics.IndicesNum
 //
 // The rule in which DrawTriangles works effectively is same as DrawImage's.
 //
-// In contrast to DrawImage, DrawTriangles doesn't care source image edges.
-// This means that you might need to add 1px gap on a source region when you render an image by DrawTriangles.
-// Note that Ebiten creates texture atlases internally, so you still have to care this even when
-// you render a single image.
-//
 // When the image i is disposed, DrawTriangles does nothing.
 //
 // Internal mipmap is not used on DrawTriangles.
@@ -468,10 +464,6 @@ func (i *Image) DrawTriangles(vertices []Vertex, indices []uint16, img *Image, o
 		return
 	}
 
-	// TODO: Implement this.
-	if img.isSubimage() {
-		panic("using a subimage at DrawTriangles is not implemented")
-	}
 	if i.isSubimage() {
 		panic("render to a subimage is not implemented")
 	}
@@ -499,8 +491,12 @@ func (i *Image) DrawTriangles(vertices []Vertex, indices []uint16, img *Image, o
 
 	vs := make([]float32, len(vertices)*graphics.VertexFloatNum)
 	src := img.mipmap.original()
+	r := img.Bounds()
 	for idx, v := range vertices {
-		src.PutVertex(vs[idx*graphics.VertexFloatNum:(idx+1)*graphics.VertexFloatNum], float32(v.DstX), float32(v.DstY), v.SrcX, v.SrcY, v.ColorR, v.ColorG, v.ColorB, v.ColorA)
+		src.PutVertex(vs[idx*graphics.VertexFloatNum:(idx+1)*graphics.VertexFloatNum],
+			float32(v.DstX), float32(v.DstY), v.SrcX, v.SrcY,
+			float32(r.Min.X), float32(r.Min.Y), float32(r.Max.X), float32(r.Max.Y),
+			v.ColorR, v.ColorG, v.ColorB, v.ColorA)
 	}
 	i.mipmap.original().DrawImage(img.mipmap.original(), vs, indices, options.ColorM.impl, mode, filter)
 	i.disposeMipmaps()

image_test.go

@@ -606,15 +606,72 @@ func TestImageEdge(t *testing.T) {
 	for _, s := range []float64{1, 0.5, 0.25} {
 		for _, f := range []Filter{FilterNearest, FilterLinear} {
 			for _, a := range angles {
+				for _, testDrawTriangles := range []bool{false, true} {
 					img1.Clear()
-				op := &DrawImageOptions{}
 					w, h := img0Sub.Size()
-				op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
+					b := img0Sub.Bounds()
-				op.GeoM.Scale(s, s)
+					var geo GeoM
-				op.GeoM.Rotate(a)
+					geo.Translate(-float64(w)/2, -float64(h)/2)
-				op.GeoM.Translate(img1Width/2, img1Height/2)
+					geo.Scale(s, s)
+					geo.Rotate(a)
+					geo.Translate(img1Width/2, img1Height/2)
+					if !testDrawTriangles {
+						op := &DrawImageOptions{}
+						op.GeoM = geo
 						op.Filter = f
 						img1.DrawImage(img0Sub, op)
+					} else {
+						op := &DrawTrianglesOptions{}
+						dx0, dy0 := geo.Apply(0, 0)
+						dx1, dy1 := geo.Apply(float64(w), 0)
+						dx2, dy2 := geo.Apply(0, float64(h))
+						dx3, dy3 := geo.Apply(float64(w), float64(h))
+						vs := []Vertex{
+							{
+								DstX:   float32(dx0),
+								DstY:   float32(dy0),
+								SrcX:   float32(b.Min.X),
+								SrcY:   float32(b.Min.Y),
+								ColorR: 1,
+								ColorG: 1,
+								ColorB: 1,
+								ColorA: 1,
+							},
+							{
+								DstX:   float32(dx1),
+								DstY:   float32(dy1),
+								SrcX:   float32(b.Max.X),
+								SrcY:   float32(b.Min.Y),
+								ColorR: 1,
+								ColorG: 1,
+								ColorB: 1,
+								ColorA: 1,
+							},
+							{
+								DstX:   float32(dx2),
+								DstY:   float32(dy2),
+								SrcX:   float32(b.Min.X),
+								SrcY:   float32(b.Max.Y),
+								ColorR: 1,
+								ColorG: 1,
+								ColorB: 1,
+								ColorA: 1,
+							},
+							{
+								DstX:   float32(dx3),
+								DstY:   float32(dy3),
+								SrcX:   float32(b.Max.X),
+								SrcY:   float32(b.Max.Y),
+								ColorR: 1,
+								ColorG: 1,
+								ColorB: 1,
+								ColorA: 1,
+							},
+						}
+						is := graphics.QuadIndices()
+						op.Filter = f
+						img1.DrawTriangles(vs, is, img0Sub, op)
+					}
 					allTransparent := true
 					for j := 0; j < img1Height; j++ {
 						for i := 0; i < img1Width; i++ {
@@ -633,11 +690,12 @@ func TestImageEdge(t *testing.T) {
 									continue
 								}
 							}
-						t.Fatalf("img1.At(%d, %d) (filter: %d, scale: %f, angle: %f) want: red or transparent, got: %v", i, j, f, s, a, c)
+							t.Fatalf("img1.At(%d, %d) (filter: %d, scale: %f, angle: %f, draw-triangles?: %t) want: red or transparent, got: %v", i, j, f, s, a, testDrawTriangles, c)
 						}
 					}
 					if allTransparent {
-					t.Fatalf("img1 (filter: %d, scale: %f, angle: %f) is transparent but should not", f, s, a)
+						t.Fatalf("img1 (filter: %d, scale: %f, angle: %f, draw-triangles?: %t) is transparent but should not", f, s, a, testDrawTriangles)
+					}
 				}
 			}
 		}

internal/graphics/vertices.go

@@ -155,7 +155,7 @@ func QuadIndices() []uint16 {
 	return quadIndices
 }
 
-func PutVertex(vs []float32, width, height int, dx, dy, sx, sy float32, cr, cg, cb, ca float32) {
+func PutVertex(vs []float32, width, height int, dx, dy, su, sv float32, u0, v0, u1, v1 float32, cr, cg, cb, ca float32) {
 	if !isPowerOf2(width) {
 		panic("not reached")
 	}
@@ -163,21 +163,14 @@ func PutVertex(vs []float32, width, height int, dx, dy, sx, sy float32, cr, cg,
 		panic("not reached")
 	}
 
-	wf := float32(width)
-	hf := float32(height)
-
-	// Specify -1 for the source region, which means the source region is ignored.
-	//
-	// NaN would make more sense to represent an invalid state, but vertices including NaN values doesn't work on
-	// some machines (#696). Let's use negative numbers to represent such state.
 	vs[0] = dx
 	vs[1] = dy
-	vs[2] = sx / wf
+	vs[2] = su
-	vs[3] = sy / hf
+	vs[3] = sv
-	vs[4] = 0
+	vs[4] = u0
-	vs[5] = 0
+	vs[5] = v0
-	vs[6] = 1
+	vs[6] = u1
-	vs[7] = 1
+	vs[7] = v1
 	vs[8] = cr
 	vs[9] = cg
 	vs[10] = cb

internal/shareable/shareable.go

@@ -197,13 +197,23 @@ func (i *Image) QuadVertices(sx0, sy0, sx1, sy1 int, a, b, c, d, tx, ty float32,
 	return graphics.QuadVertices(w, h, sx0+ox, sy0+oy, sx1+ox, sy1+oy, a, b, c, d, tx, ty, cr, cg, cb, ca)
 }
 
-func (i *Image) PutVertex(dest []float32, dx, dy, sx, sy float32, cr, cg, cb, ca float32) {
+func (i *Image) PutVertex(dest []float32, dx, dy, sx, sy float32, bx0, by0, bx1, by1 float32,
+	cr, cg, cb, ca float32) {
 	if i.backend == nil {
 		i.allocate(true)
 	}
 	ox, oy, _, _ := i.region()
+	oxf, oyf := float32(ox), float32(oy)
 	w, h := i.backend.restorable.SizePowerOf2()
-	graphics.PutVertex(dest, w, h, dx, dy, sx+float32(ox), sy+float32(oy), cr, cg, cb, ca)
+
+	su := (sx + oxf) / float32(w)
+	sv := (sy + oyf) / float32(h)
+	u0 := (bx0 + oxf) / float32(w)
+	v0 := (by0 + oyf) / float32(h)
+	u1 := (bx1 + oxf) / float32(w)
+	v1 := (by1 + oyf) / float32(h)
+
+	graphics.PutVertex(dest, w, h, dx, dy, su, sv, u0, v0, u1, v1, cr, cg, cb, ca)
 }
 
 const MaxCountForShare = 10