From 79326025afbe4d6dc8d484a2cffc6a3091a0bd25 Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Tue, 23 Jun 2020 12:48:35 -0700
Subject: [PATCH] Rework the blit shader

---
 resources/shaders/gl3/blit.fs.glsl    | 2 +-
 resources/shaders/gl3/blit.vs.glsl    | 9 +++++----
 resources/shaders/gl4/blit.fs.glsl    | 2 +-
 resources/shaders/gl4/blit.vs.glsl    | 9 +++++----
 resources/shaders/metal/blit.fs.metal | 2 +-
 resources/shaders/metal/blit.vs.metal | 6 +++---
 shaders/blit.fs.glsl                  | 2 +-
 shaders/blit.vs.glsl                  | 9 +++++----
 8 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/resources/shaders/gl3/blit.fs.glsl b/resources/shaders/gl3/blit.fs.glsl
index b32fc956..85092e27 100644
--- a/resources/shaders/gl3/blit.fs.glsl
+++ b/resources/shaders/gl3/blit.fs.glsl
@@ -26,6 +26,6 @@ out vec4 oFragColor;
 
 void main(){
     vec4 color = texture(uSrc, vTexCoord);
-    oFragColor = vec4(color . rgb * color . a, color . a);
+    oFragColor = color;
 }
 
diff --git a/resources/shaders/gl3/blit.vs.glsl b/resources/shaders/gl3/blit.vs.glsl
index 6c9391d5..98909d95 100644
--- a/resources/shaders/gl3/blit.vs.glsl
+++ b/resources/shaders/gl3/blit.vs.glsl
@@ -18,16 +18,17 @@ precision highp float;
 
 
 
+uniform vec4 uDestRect;
+uniform vec2 uFramebufferSize;
+
 in ivec2 aPosition;
 
 out vec2 vTexCoord;
 
 void main(){
+    vec2 position = mix(uDestRect . xy, uDestRect . zw, vec2(aPosition))/ uFramebufferSize;
     vec2 texCoord = vec2(aPosition);
-
-
-
     vTexCoord = texCoord;
-    gl_Position = vec4(mix(vec2(- 1.0), vec2(1.0), vec2(aPosition)), 0.0, 1.0);
+    gl_Position = vec4(mix(vec2(- 1.0), vec2(1.0), position), 0.0, 1.0);
 }
 
diff --git a/resources/shaders/gl4/blit.fs.glsl b/resources/shaders/gl4/blit.fs.glsl
index b32fc956..85092e27 100644
--- a/resources/shaders/gl4/blit.fs.glsl
+++ b/resources/shaders/gl4/blit.fs.glsl
@@ -26,6 +26,6 @@ out vec4 oFragColor;
 
 void main(){
     vec4 color = texture(uSrc, vTexCoord);
-    oFragColor = vec4(color . rgb * color . a, color . a);
+    oFragColor = color;
 }
 
diff --git a/resources/shaders/gl4/blit.vs.glsl b/resources/shaders/gl4/blit.vs.glsl
index 6c9391d5..98909d95 100644
--- a/resources/shaders/gl4/blit.vs.glsl
+++ b/resources/shaders/gl4/blit.vs.glsl
@@ -18,16 +18,17 @@ precision highp float;
 
 
 
+uniform vec4 uDestRect;
+uniform vec2 uFramebufferSize;
+
 in ivec2 aPosition;
 
 out vec2 vTexCoord;
 
 void main(){
+    vec2 position = mix(uDestRect . xy, uDestRect . zw, vec2(aPosition))/ uFramebufferSize;
     vec2 texCoord = vec2(aPosition);
-
-
-
     vTexCoord = texCoord;
-    gl_Position = vec4(mix(vec2(- 1.0), vec2(1.0), vec2(aPosition)), 0.0, 1.0);
+    gl_Position = vec4(mix(vec2(- 1.0), vec2(1.0), position), 0.0, 1.0);
 }
 
diff --git a/resources/shaders/metal/blit.fs.metal b/resources/shaders/metal/blit.fs.metal
index cb0ab32a..d7a4afb2 100644
--- a/resources/shaders/metal/blit.fs.metal
+++ b/resources/shaders/metal/blit.fs.metal
@@ -18,7 +18,7 @@ fragment main0_out main0(main0_in in [[stage_in]], texture2d<float> uSrc [[textu
 {
     main0_out out = {};
     float4 color = uSrc.sample(uSrcSmplr, in.vTexCoord);
-    out.oFragColor = float4(color.xyz * color.w, color.w);
+    out.oFragColor = color;
     return out;
 }
 
diff --git a/resources/shaders/metal/blit.vs.metal b/resources/shaders/metal/blit.vs.metal
index 701d97f0..35de802e 100644
--- a/resources/shaders/metal/blit.vs.metal
+++ b/resources/shaders/metal/blit.vs.metal
@@ -15,13 +15,13 @@ struct main0_in
     int2 aPosition [[attribute(0)]];
 };
 
-vertex main0_out main0(main0_in in [[stage_in]])
+vertex main0_out main0(main0_in in [[stage_in]], constant float4& uDestRect [[buffer(0)]], constant float2& uFramebufferSize [[buffer(1)]])
 {
     main0_out out = {};
+    float2 position = mix(uDestRect.xy, uDestRect.zw, float2(in.aPosition)) / uFramebufferSize;
     float2 texCoord = float2(in.aPosition);
-    texCoord.y = 1.0 - texCoord.y;
     out.vTexCoord = texCoord;
-    out.gl_Position = float4(mix(float2(-1.0), float2(1.0), float2(in.aPosition)), 0.0, 1.0);
+    out.gl_Position = float4(mix(float2(-1.0), float2(1.0), position), 0.0, 1.0);
     return out;
 }
 
diff --git a/shaders/blit.fs.glsl b/shaders/blit.fs.glsl
index 8d461ed4..e257ba64 100644
--- a/shaders/blit.fs.glsl
+++ b/shaders/blit.fs.glsl
@@ -24,5 +24,5 @@ out vec4 oFragColor;
 
 void main() {
     vec4 color = texture(uSrc, vTexCoord);
-    oFragColor = vec4(color.rgb * color.a, color.a);
+    oFragColor = color;
 }
diff --git a/shaders/blit.vs.glsl b/shaders/blit.vs.glsl
index ca3b0f7c..9077fa8a 100644
--- a/shaders/blit.vs.glsl
+++ b/shaders/blit.vs.glsl
@@ -16,15 +16,16 @@ precision highp float;
 precision highp sampler2D;
 #endif
 
+uniform vec4 uDestRect;
+uniform vec2 uFramebufferSize;
+
 in ivec2 aPosition;
 
 out vec2 vTexCoord;
 
 void main() {
+    vec2 position = mix(uDestRect.xy, uDestRect.zw, vec2(aPosition)) / uFramebufferSize;
     vec2 texCoord = vec2(aPosition);
-#ifdef PF_ORIGIN_UPPER_LEFT
-    texCoord.y = 1.0 - texCoord.y;
-#endif
     vTexCoord = texCoord;
-    gl_Position = vec4(mix(vec2(-1.0), vec2(1.0), vec2(aPosition)), 0.0, 1.0);
+    gl_Position = vec4(mix(vec2(-1.0), vec2(1.0), position), 0.0, 1.0);
 }