From 1785b6a670b211e2d976eb78e1a2588ad35389d6 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Mon, 15 Jun 2020 00:17:13 +0900
Subject: [PATCH] examples/moire: Add a smaller scale, and remove AdjustTexel
 function from shaders

This can reproduce the bug reported at #669.

Apparently, the fix (8827520d4a480b5e5259d2220ddec676caa5bd09) is
no longer required after 3550abef7a25ecf548b3711d4ea64be1f08aa226.
That's pretty odd, but examples/moire proves this fact.

Updates #669
Updates #759
---
 examples/moire/main.go                          |  4 +++-
 internal/graphicsdriver/metal/graphics.go       | 15 ---------------
 internal/graphicsdriver/opengl/defaultshader.go | 17 -----------------
 3 files changed, 3 insertions(+), 33 deletions(-)

diff --git a/examples/moire/main.go b/examples/moire/main.go
index e2f9bd94b..dcf01c9bd 100644
--- a/examples/moire/main.go
+++ b/examples/moire/main.go
@@ -71,12 +71,14 @@ func (g *game) Update(screen *ebiten.Image) error {
 
 	if inpututil.IsKeyJustPressed(ebiten.KeyS) {
 		switch g.scale {
+		case 0.5:
+			g.scale = 1
 		case 1:
 			g.scale = 1.5
 		case 1.5:
 			g.scale = 2
 		case 2:
-			g.scale = 1
+			g.scale = 0.5
 		default:
 			panic("not reached")
 		}
diff --git a/internal/graphicsdriver/metal/graphics.go b/internal/graphicsdriver/metal/graphics.go
index d3327aedf..eb591bd0c 100644
--- a/internal/graphicsdriver/metal/graphics.go
+++ b/internal/graphicsdriver/metal/graphics.go
@@ -93,19 +93,6 @@ vertex VertexOut VertexShader(
   return out;
 }
 
-// AdjustTexels adjust texels.
-// See #669, #759
-float2 AdjustTexel(float2 source_size, float2 p0, float2 p1) {
-  const float2 texel_size = 1.0 / source_size;
-  if (fract((p1.x-p0.x)*source_size.x) == 0.0) {
-    p1.x -= texel_size.x / 512.0;
-  }
-  if (fract((p1.y-p0.y)*source_size.y) == 0.0) {
-    p1.y -= texel_size.y / 512.0;
-  }
-  return p1;
-}
-
 float FloorMod(float x, float y) {
   if (x < 0.0) {
     return y - (-x - y * floor(-x/y));
@@ -154,7 +141,6 @@ struct ColorFromTexel<FILTER_LINEAR, address> {
 
     float2 p0 = v.tex - texel_size / 2.0;
     float2 p1 = v.tex + texel_size / 2.0;
-    p1 = AdjustTexel(source_size, p0, p1);
     p0 = AdjustTexelByAddress<address>(p0, v.tex_region);
     p1 = AdjustTexelByAddress<address>(p1, v.tex_region);
 
@@ -193,7 +179,6 @@ struct ColorFromTexel<FILTER_SCREEN, address> {
 
     float2 p0 = v.tex - texel_size / 2.0 / scale;
     float2 p1 = v.tex + texel_size / 2.0 / scale;
-    p1 = AdjustTexel(source_size, p0, p1);
 
     float4 c0 = texture.sample(texture_sampler, p0);
     float4 c1 = texture.sample(texture_sampler, float2(p1.x, p0.y));
diff --git a/internal/graphicsdriver/opengl/defaultshader.go b/internal/graphicsdriver/opengl/defaultshader.go
index ba29885b4..80e15f264 100644
--- a/internal/graphicsdriver/opengl/defaultshader.go
+++ b/internal/graphicsdriver/opengl/defaultshader.go
@@ -156,20 +156,6 @@ varying highp vec2 varying_tex;
 varying highp vec4 varying_tex_region;
 varying highp vec4 varying_color_scale;
 
-// adjustTexel adjusts the two texels and returns the adjusted second texel.
-// When p1 - p0 is exactly equal to the texel size, jaggy can happen on macOS (#669).
-// In order to avoid this jaggy, subtract a little bit from the second texel.
-highp vec2 adjustTexel(highp vec2 p0, highp vec2 p1) {
-  highp vec2 texel_size = 1.0 / source_size;
-  if (fract((p1.x-p0.x)*source_size.x) == 0.0) {
-    p1.x -= texel_size.x / 512.0;
-  }
-  if (fract((p1.y-p0.y)*source_size.y) == 0.0) {
-    p1.y -= texel_size.y / 512.0;
-  }
-  return p1;
-}
-
 highp float floorMod(highp float x, highp float y) {
   if (x < 0.0) {
     return y - (-x - y * floor(-x/y));
@@ -211,7 +197,6 @@ void main(void) {
   highp vec2 p0 = pos - texel_size / 2.0;
   highp vec2 p1 = pos + texel_size / 2.0;
 
-  p1 = adjustTexel(p0, p1);
   p0 = adjustTexelByAddress(p0, varying_tex_region);
   p1 = adjustTexelByAddress(p1, varying_tex_region);
 
@@ -246,8 +231,6 @@ void main(void) {
   highp vec2 p0 = pos - half_scaled_texel_size;
   highp vec2 p1 = pos + half_scaled_texel_size;
 
-  p1 = adjustTexel(p0, p1);
-
   vec4 c0 = texture2D(texture, p0);
   vec4 c1 = texture2D(texture, vec2(p1.x, p0.y));
   vec4 c2 = texture2D(texture, vec2(p0.x, p1.y));