From e3401efccb23e51d7e458f3ec8a4d016e949ae4e Mon Sep 17 00:00:00 2001
From: Christopher Tenter <christopher.tenter@rwth-aachen.de>
Date: Mon, 7 Apr 2014 15:10:12 +0000
Subject: [PATCH] - safety check in msaa sample weight computation - add msaa
 shaders

git-svn-id: http://www.openflipper.org/svnrepo/OpenFlipper/branches/Free@18437 383ad7c9-94d9-4d36-a494-682f7c89f535
---
 Shaders/MSAA/msaa.glsl           | 102 +++++++++++++++++++++++++++++++
 Shaders/MSAA/sample_linear.glsl  |  16 +++++
 Shaders/MSAA/sample_nearest.glsl |  16 +++++
 3 files changed, 134 insertions(+)
 create mode 100644 Shaders/MSAA/msaa.glsl
 create mode 100644 Shaders/MSAA/sample_linear.glsl
 create mode 100644 Shaders/MSAA/sample_nearest.glsl

diff --git a/Shaders/MSAA/msaa.glsl b/Shaders/MSAA/msaa.glsl
new file mode 100644
index 00000000..8dc7cd02
--- /dev/null
+++ b/Shaders/MSAA/msaa.glsl
@@ -0,0 +1,102 @@
+// methods for resolving multisampled textures
+
+
+vec4 ReadMultisampledTexture(in sampler2DMS tex, in ivec2 pos, in int numSamples)
+{
+  vec4 texel = vec4(0,0,0,0);
+  for (int i = 0; i < numSamples; ++i)
+  {
+	vec4 sample = texelFetch(tex, pos, i);
+	
+	texel += sample;
+  }
+  
+  return texel / float(numSamples);
+}
+
+vec4 ReadMultisampledTexture(in sampler2DMS tex, in vec2 texcood, in int numSamples)
+{
+  ivec2 pos = int(floor(texcoord));
+  return ReadMultisampledTexture(tex, pos, numSamples);
+}
+
+
+vec4 ReadMultisampledTexture(in sampler2DMS tex, in ivec2 pos, in int numSamples, in samplerBuffer filterWeights)
+{
+  vec4 texel = vec4(0,0,0,0);
+  for (int i = 0; i < numSamples; ++i)
+  {
+    float filterWeight = texelFetch(filterWeights, i).x;
+	vec4 sample = texelFetch(tex, pos, i);
+	
+	texel += filterWeight * sample;
+  }
+  
+  return texel;
+}
+
+vec4 ReadMultisampledTexture(in sampler2DMS tex, in vec2 texcood, in int numSamples, in samplerBuffer filterWeights)
+{
+  ivec2 pos = int(floor(texcoord));
+  return ReadMultisampledTexture(tex, pos, numSamples, filterWeights);
+}
+
+
+vec4 FilterMultisampledTextureBilinear(in sampler2DMS tex, in vec2 texcoord, in int numSamples)
+{
+  ivec2 texSize = textureSize(tex);
+  
+  // top-left texel position
+  vec2 pos00 = floor( texSize * texcoord );
+  ivec2 loc00 = ivec2(pos00);
+  
+  // lerp weights
+  vec2 alpha = fract( texSize * texcoord );
+
+  // bilinear filtering
+
+  // lerp in u-direction top
+  vec4 sampleX0 = mix(
+    ReadMultisampledTexture(tex, loc00, numSamples),
+    ReadMultisampledTexture(tex, loc00 + ivec2(1,0), numSamples),
+	alpha.x);
+			
+  // lerp in u-direction bottom
+  vec4 sampleX1 = mix(
+    ReadMultisampledTexture(tex, loc00 + ivec2(0,1), numSamples),
+    ReadMultisampledTexture(tex, loc00 + ivec2(1,1), numSamples),
+	alpha.x);
+  
+  // lerp in v direction
+  return mix(sampleX0, sampleX1, alpha.y);
+}
+
+
+vec4 FilterMultisampledTextureBilinear(in sampler2DMS tex, in vec2 texcoord, in int numSamples, in samplerBuffer filterWeights)
+{
+  ivec2 texSize = textureSize(tex);
+  
+  // top-left texel position
+  vec2 pos00 = floor( texSize * texcoord );
+  ivec2 loc00 = ivec2(pos00);
+  
+  // lerp weights
+  vec2 alpha = fract( texSize * texcoord );
+
+  // bilinear filtering
+
+  // lerp in u-direction top
+  vec4 sampleX0 = mix(
+    ReadMultisampledTexture(tex, loc00, numSamples, filterWeights),
+    ReadMultisampledTexture(tex, loc00 + ivec2(1,0), numSamples, filterWeights),
+	alpha.x);
+			
+  // lerp in u-direction bottom
+  vec4 sampleX1 = mix(
+    ReadMultisampledTexture(tex, loc00 + ivec2(0,1), numSamples, filterWeights),
+    ReadMultisampledTexture(tex, loc00 + ivec2(1,1), numSamples, filterWeights),
+	alpha.x);
+  
+  // lerp in v direction
+  return mix(sampleX0, sampleX1, alpha.y);
+}
\ No newline at end of file
diff --git a/Shaders/MSAA/sample_linear.glsl b/Shaders/MSAA/sample_linear.glsl
new file mode 100644
index 00000000..09cd1235
--- /dev/null
+++ b/Shaders/MSAA/sample_linear.glsl
@@ -0,0 +1,16 @@
+#version 150
+
+#include "msaa.glsl"
+
+
+uniform sampler2DMS inputTex;
+uniform int numSamples;
+
+in vec2 vTexCoord;
+out vec4 outFragment;
+
+
+void main()
+{
+  outFragment = FilterMultisampledTextureBilinear(inputTex, vTexCoord, numSamples);
+}
\ No newline at end of file
diff --git a/Shaders/MSAA/sample_nearest.glsl b/Shaders/MSAA/sample_nearest.glsl
new file mode 100644
index 00000000..b0d0cb54
--- /dev/null
+++ b/Shaders/MSAA/sample_nearest.glsl
@@ -0,0 +1,16 @@
+#version 150
+
+#include "msaa.glsl"
+
+
+uniform sampler2DMS inputTex;
+uniform int numSamples;
+
+in vec2 vTexCoord;
+out vec4 outFragment;
+
+
+void main()
+{
+  outFragment = ReadMultisampledTexture(inputTex, vTexCoord, numSamples);
+}
\ No newline at end of file
-- 
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