graphics: Limit source-rectangle range

Remove texture adjustment introduced due to #317

image_test.go

@@ -529,10 +529,8 @@ func TestImageEdge(t *testing.T) {
 	}
 	red := color.RGBA{0xff, 0, 0, 0xff}
 	transparent := color.RGBA{0, 0, 0, 0}
-	// Unfortunately, TravisCI couldn't pass this test for some angles.
+
-	// https://travis-ci.org/hajimehoshi/ebiten/builds/200454658
+	for a := 0; a < 360; a += 5 {
-	// Let's use 'decent' angles here.
-	for _, a := range []int{0, 45, 90, 135, 180, 225, 270, 315, 360} {
 		if err := img1.Clear(); err != nil {
 			t.Fatal(err)
 		}

internal/graphics/program.go

@@ -92,7 +92,7 @@ var (
 			{
 				name:      "tex_coord",
 				dataType:  opengl.Float,
-				num:       2,
+				num:       4,
 				normalize: false,
 			},
 			{

internal/graphics/shader.go

@@ -29,13 +29,19 @@ var shaders = map[shaderId]string{
 	shaderVertexModelview: `
 uniform mat4 projection_matrix;
 attribute vec2 vertex;
-attribute vec2 tex_coord;
+attribute vec4 tex_coord;
 attribute vec4 geo_matrix_body;
 attribute vec2 geo_matrix_translation;
 varying vec2 vertex_out_tex_coord;
+varying vec2 vertex_out_tex_coord_min;
+varying vec2 vertex_out_tex_coord_max;
 
 void main(void) {
-  vertex_out_tex_coord = tex_coord;
+  vertex_out_tex_coord = vec2(tex_coord[0], tex_coord[1]);
+  vertex_out_tex_coord_min =
+    vec2(min(tex_coord[0], tex_coord[2]), min(tex_coord[1], tex_coord[3]));
+  vertex_out_tex_coord_max =
+    vec2(max(tex_coord[0], tex_coord[2]), max(tex_coord[1], tex_coord[3]));
   mat4 geo_matrix = mat4(
     vec4(geo_matrix_body[0], geo_matrix_body[2], 0, 0),
     vec4(geo_matrix_body[1], geo_matrix_body[3], 0, 0),
@@ -58,9 +64,17 @@ uniform sampler2D texture;
 uniform mat4 color_matrix;
 uniform vec4 color_matrix_translation;
 varying vec2 vertex_out_tex_coord;
+varying vec2 vertex_out_tex_coord_min;
+varying vec2 vertex_out_tex_coord_max;
 
 void main(void) {
-  vec4 color = texture2D(texture, vertex_out_tex_coord);
+  vec4 color = vec4(0, 0, 0, 0);
+  if (vertex_out_tex_coord_min.x <= vertex_out_tex_coord.x &&
+      vertex_out_tex_coord_min.y <= vertex_out_tex_coord.y &&
+      vertex_out_tex_coord.x < vertex_out_tex_coord_max.x &&
+      vertex_out_tex_coord.y < vertex_out_tex_coord_max.y) {
+    color = texture2D(texture, vertex_out_tex_coord);
+  }
 
   // Un-premultiply alpha
   if (0.0 < color.a) {

internal/restorable/images_test.go

@@ -75,11 +75,13 @@ func vertices(sw, sh int, x, y int) []float32 {
 	shf := float32(sh)
 	tx := float32(x)
 	ty := float32(y)
+
+	// For the rule of values, see vertices.go.
 	return []float32{
-		0, 0, 0, 0, a, b, c, d, tx, ty,
+		0, 0, 0, 0, 1, 1, a, b, c, d, tx, ty,
-		0, shf, 0, 1, a, b, c, d, tx, ty,
+		0, shf, 0, 1, 1, 0, a, b, c, d, tx, ty,
-		swf, 0, 1, 0, a, b, c, d, tx, ty,
+		swf, 0, 1, 0, 0, 1, a, b, c, d, tx, ty,
-		swf, shf, 1, 1, a, b, c, d, tx, ty,
+		swf, shf, 1, 1, 0, 0, a, b, c, d, tx, ty,
 	}
 }
 

vertices.go

@@ -19,12 +19,6 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/restorable"
 )
 
-// texelAdjustment represents a number to be used to adjust texel.
-// Texels are adjusted by amount propotional to inverse of texelAdjustment.
-// This is necessary not to use unexpected pixels outside of texels.
-// See #317.
-var texelAdjustment float32 = 256
-
 var (
 	quadFloat32Num     = restorable.QuadVertexSizeInBytes() / 4
 	theVerticesBackend = &verticesBackend{}
@@ -74,54 +68,65 @@ func vertices(sx0, sy0, sx1, sy1 int, width, height int, geo *affine.GeoM) []flo
 	hf := float32(h)
 	x0, y0, x1, y1 := float32(0), float32(0), float32(sx1-sx0), float32(sy1-sy0)
 	u0, v0, u1, v1 := float32(sx0)/wf, float32(sy0)/hf, float32(sx1)/wf, float32(sy1)/hf
-	// Adjust texels to fix a problem that outside texels are used (#317).
+
-	if texelAdjustment > 0 {
+	// Vertex coordinates
-		u1 -= 1.0 / wf / texelAdjustment
-		v1 -= 1.0 / hf / texelAdjustment
-	}
 	vs[0] = x0
 	vs[1] = y0
+
+	// Texture coordinates: first 2 values indicates the actual coodinate, and
+	// the second indicates diagonally opposite coodinates.
+	// The second is needed to calculate source rectangle size in shader programs.
 	vs[2] = u0
 	vs[3] = v0
-	vs[4] = g0
+	vs[4] = u1
-	vs[5] = g1
+	vs[5] = v1
-	vs[6] = g2
-	vs[7] = g3
-	vs[8] = g4
-	vs[9] = g5
 
-	vs[10] = x1
+	// Geometry matrix
-	vs[11] = y0
+	vs[6] = g0
-	vs[12] = u1
+	vs[7] = g1
-	vs[13] = v0
+	vs[8] = g2
-	vs[14] = g0
+	vs[9] = g3
-	vs[15] = g1
+	vs[10] = g4
-	vs[16] = g2
+	vs[11] = g5
-	vs[17] = g3
-	vs[18] = g4
-	vs[19] = g5
 
-	vs[20] = x0
+	vs[12] = x1
-	vs[21] = y1
+	vs[13] = y0
-	vs[22] = u0
+	vs[14] = u1
-	vs[23] = v1
+	vs[15] = v0
-	vs[24] = g0
+	vs[16] = u0
-	vs[25] = g1
+	vs[17] = v1
-	vs[26] = g2
+	vs[18] = g0
-	vs[27] = g3
+	vs[19] = g1
-	vs[28] = g4
+	vs[20] = g2
-	vs[29] = g5
+	vs[21] = g3
+	vs[22] = g4
+	vs[23] = g5
 
-	vs[30] = x1
+	vs[24] = x0
-	vs[31] = y1
+	vs[25] = y1
-	vs[32] = u1
+	vs[26] = u0
-	vs[33] = v1
+	vs[27] = v1
-	vs[34] = g0
+	vs[28] = u1
-	vs[35] = g1
+	vs[29] = v0
-	vs[36] = g2
+	vs[30] = g0
-	vs[37] = g3
+	vs[31] = g1
-	vs[38] = g4
+	vs[32] = g2
-	vs[39] = g5
+	vs[33] = g3
+	vs[34] = g4
+	vs[35] = g5
+
+	vs[36] = x1
+	vs[37] = y1
+	vs[38] = u1
+	vs[39] = v1
+	vs[40] = u0
+	vs[41] = v0
+	vs[42] = g0
+	vs[43] = g1
+	vs[44] = g2
+	vs[45] = g3
+	vs[46] = g4
+	vs[47] = g5
 
 	return vs
 }

vertices_ios.go

@@ -1,22 +0,0 @@
-// Copyright 2017 The Ebiten Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// +build ios
-
-package ebiten
-
-func init() {
-	// Texel adjustment causes glitches on iOS.
-	texelAdjustment = 0
-}

vertices_notios.go

@@ -1,28 +0,0 @@
-// Copyright 2017 The Ebiten Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// +build !ios
-
-package ebiten
-
-import (
-	"github.com/hajimehoshi/ebiten/internal/web"
-)
-
-func init() {
-	if web.IsIOSSafari() {
-		// Texel adjustment causes glitches on iOS.
-		texelAdjustment = 0
-	}
-}