From 742bbb4ccd07420063253df8998e4eaf74b1608a Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 17 Feb 2019 15:04:59 +0900
Subject: [PATCH] graphicsdriver: Simplify clamping color values

For negative values, OpenGL (and Metal) should take care of them
so we don't have to care.
---
 internal/graphicsdriver/metal/driver.go  | 3 +--
 internal/graphicsdriver/opengl/shader.go | 4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/internal/graphicsdriver/metal/driver.go b/internal/graphicsdriver/metal/driver.go
index e111e2a66..e9116216c 100644
--- a/internal/graphicsdriver/metal/driver.go
+++ b/internal/graphicsdriver/metal/driver.go
@@ -206,13 +206,12 @@ float4 FragmentShaderImpl(
     c.rgb /= c.a + (1.0 - sign(c.a));
     c = (color_matrix_body * c) + color_matrix_translation;
     c *= v.color;
-    c = clamp(c, 0.0, 1.0);
     c.rgb *= c.a;
   } else {
     float4 s = v.color;
     c *= float4(s.r, s.g, s.b, 1.0) * s.a;
-    c = clamp(c, 0.0, c.a);
   }
+  c = min(c, c.a);
   return c;
 }
 
diff --git a/internal/graphicsdriver/opengl/shader.go b/internal/graphicsdriver/opengl/shader.go
index 8941ad33f..f31eb4e6e 100644
--- a/internal/graphicsdriver/opengl/shader.go
+++ b/internal/graphicsdriver/opengl/shader.go
@@ -263,15 +263,15 @@ void main(void) {
   // Apply the color matrix or scale.
   color = (color_matrix_body * color) + color_matrix_translation;
   color *= varying_color_scale;
-  color = clamp(color, 0.0, 1.0);
   // Premultiply alpha
   color.rgb *= color.a;
 #else
   vec4 s = varying_color_scale;
   color *= vec4(s.r, s.g, s.b, 1.0) * s.a;
-  color = clamp(color, 0.0, color.a);
 #endif
 
+  color = min(color, color.a);
+
   gl_FragColor = color;
 }
 `