From 590672d03554587c42224bdfbc387ba51d5b2d19 Mon Sep 17 00:00:00 2001
From: Andrzej Kapolka <drzej.k@gmail.com>
Date: Tue, 20 Aug 2013 17:02:35 -0700
Subject: [PATCH] Fewer texture lookups when diffusing.

---
 interface/resources/shaders/diffuse.frag | 19 +++++++++----------
 interface/src/renderer/GlowEffect.cpp    |  6 ++++++
 interface/src/renderer/GlowEffect.h      |  1 +
 3 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/interface/resources/shaders/diffuse.frag b/interface/resources/shaders/diffuse.frag
index f8be7075db..6ad77c860e 100644
--- a/interface/resources/shaders/diffuse.frag
+++ b/interface/resources/shaders/diffuse.frag
@@ -14,15 +14,14 @@ uniform sampler2D originalTexture;
 // the texture containing the diffused color
 uniform sampler2D diffusedTexture;
 
+// the scale of diffusion
+uniform vec2 diffusionScale;
+
 void main(void) {
-    float ds = dFdx(gl_TexCoord[0].s);
-    float dt = dFdy(gl_TexCoord[0].t);
-    gl_FragColor = (texture2D(diffusedTexture, gl_TexCoord[0].st + vec2(-ds, -dt)) +
-        texture2D(diffusedTexture, gl_TexCoord[0].st + vec2(0.0, -dt)) +
-        texture2D(diffusedTexture, gl_TexCoord[0].st + vec2(ds, -dt)) +
-        texture2D(diffusedTexture, gl_TexCoord[0].st + vec2(ds, 0.0)) +
-        texture2D(diffusedTexture, gl_TexCoord[0].st + vec2(ds, dt)) +
-        texture2D(diffusedTexture, gl_TexCoord[0].st + vec2(0.0, dt)) +
-        texture2D(diffusedTexture, gl_TexCoord[0].st + vec2(-ds, dt)) +
-        texture2D(diffusedTexture, gl_TexCoord[0].st + vec2(-ds, 0.0))) / 8.5 + texture2D(originalTexture, gl_TexCoord[0].st) * 0.1;
+    vec2 minExtents = gl_TexCoord[0].st + diffusionScale * vec2(-1.5, -1.5);
+    vec2 maxExtents = gl_TexCoord[0].st + diffusionScale * vec2(1.5, 1.5);
+    gl_FragColor = (texture2D(diffusedTexture, minExtents) +
+        texture2D(diffusedTexture, vec2(maxExtents.s, minExtents.t)) + 
+        texture2D(diffusedTexture, vec2(minExtents.s, maxExtents.t)) +
+        texture2D(diffusedTexture, maxExtents)) / 4.25 + texture2D(originalTexture, gl_TexCoord[0].st) * 0.1;
 }
diff --git a/interface/src/renderer/GlowEffect.cpp b/interface/src/renderer/GlowEffect.cpp
index 77bb136b6d..b08d0680d5 100644
--- a/interface/src/renderer/GlowEffect.cpp
+++ b/interface/src/renderer/GlowEffect.cpp
@@ -57,6 +57,8 @@ void GlowEffect::init() {
     _diffuseProgram->bind();
     _diffuseProgram->setUniformValue("diffusedTexture", 1);
     _diffuseProgram->release();
+    
+    _diffusionScaleLocation = _diffuseProgram->uniformLocation("diffusionScale");
 }
 
 void GlowEffect::prepare() {
@@ -125,7 +127,11 @@ void GlowEffect::render() {
         glBindTexture(GL_TEXTURE_2D, oldDiffusedFBO->texture());
             
         _diffuseProgram->bind();
+        QSize size = Application::getInstance()->getGLWidget()->size();
+        _diffuseProgram->setUniformValue(_diffusionScaleLocation, 1.0f / size.width(), 1.0f / size.height());
+        
         renderFullscreenQuad();
+        
         _diffuseProgram->release();
         
         newDiffusedFBO->release();
diff --git a/interface/src/renderer/GlowEffect.h b/interface/src/renderer/GlowEffect.h
index 73ed9ed881..73119365e8 100644
--- a/interface/src/renderer/GlowEffect.h
+++ b/interface/src/renderer/GlowEffect.h
@@ -57,6 +57,7 @@ private:
     ProgramObject* _verticalBlurProgram;
     ProgramObject* _addSeparateProgram;
     ProgramObject* _diffuseProgram;
+    int _diffusionScaleLocation;
     
     bool _isEmpty; ///< set when nothing in the scene is currently glowing
     bool _isOddFrame; ///< controls the alternation between texture targets in diffuse add mode