From 26d48cdad099efc061db5a223b98c056aadf15bf Mon Sep 17 00:00:00 2001
From: vlj <vljn@ovi.com>
Date: Mon, 12 May 2014 23:59:17 +0200
Subject: [PATCH] SSAO: Stronger blur + tweak param

Use another algorithm to have gaussian blur that lets us customise
radius more easily.
---
 data/shaders/gaussian17taph.frag | 35 +++++++++++++------------------
 data/shaders/gaussian17tapv.frag | 36 +++++++++++++-------------------
 data/shaders/ssao.frag           |  4 ++--
 src/graphics/render.cpp          |  2 +-
 4 files changed, 32 insertions(+), 45 deletions(-)

diff --git a/data/shaders/gaussian17taph.frag b/data/shaders/gaussian17taph.frag
index 874d22a7f..f02a49dfc 100644
--- a/data/shaders/gaussian17taph.frag
+++ b/data/shaders/gaussian17taph.frag
@@ -1,37 +1,30 @@
-// From http://rastergrid.com/blog/2010/09/efficient-gaussian-blur-with-linear-sampling/
+// From http://http.developer.nvidia.com/GPUGems3/gpugems3_ch40.html
 
 uniform sampler2D tex;
 uniform vec2 pixel;
-
+uniform float sigma = 5.;
 
 in vec2 uv;
 out vec4 FragColor;
 
 void main()
 {
-
     float X = uv.x;
     float Y = uv.y;
 
-    float offset[5] = {
-        0.,
-        1.41176470588235,
-        3.29411764705882,
-        5.17647058823529,
-        7.05882352941176
-    };
-    float weight[5] = {
-        0.196380615234375,
-        0.1888427734375,
-        0.03631591796875,
-        0.0020751953125,
-        0.000015258789062
-    };
 
-    vec4 sum = texture(tex, vec2(X, Y)) * weight[0];
-    for (int i = 1; i < 5; i++) {
-        sum += texture(tex, vec2(X - offset[i] * pixel.x, Y)) * weight[i];
-        sum += texture(tex, vec2(X + offset[i] * pixel.x, Y)) * weight[i];
+    float g0, g1, g2;
+    g0 = 1.0 / (sqrt(2.0 * 3.14) * sigma);
+    g1 = exp(-0.5 / (sigma * sigma));
+    g2 = g1 * g1;
+    vec4 sum = texture(tex, vec2(X, Y)) * g0;
+    g0 *= g1;
+    g1 *= g2;
+    for (int i = 1; i < 9; i++) {
+        sum += texture(tex, vec2(X - i * pixel.x, Y)) * g0;
+        sum += texture(tex, vec2(X + i * pixel.x, Y)) * g0;
+        g0 *= g1;
+        g1 *= g2;
     }
 
     FragColor = sum;
diff --git a/data/shaders/gaussian17tapv.frag b/data/shaders/gaussian17tapv.frag
index 00de4c4aa..01e54a8a9 100644
--- a/data/shaders/gaussian17tapv.frag
+++ b/data/shaders/gaussian17tapv.frag
@@ -1,38 +1,32 @@
-// From http://rastergrid.com/blog/2010/09/efficient-gaussian-blur-with-linear-sampling/
+// From http://http.developer.nvidia.com/GPUGems3/gpugems3_ch40.html
 
 uniform sampler2D tex;
 uniform vec2 pixel;
-
+uniform float sigma = 5.;
 
 in vec2 uv;
 out vec4 FragColor;
 
 void main()
 {
-
     float X = uv.x;
     float Y = uv.y;
 
-    float offset[5] = {
-        0.,
-        1.41176470588235,
-        3.29411764705882,
-        5.17647058823529,
-        7.05882352941176
-    };
-    float weight[5] = {
-        0.196380615234375,
-        0.1888427734375,
-        0.03631591796875,
-        0.0020751953125,
-        0.000015258789062
-    };
 
-    vec4 sum = texture(tex, vec2(X, Y)) * weight[0];
-    for (int i = 1; i < 5; i++) {
-        sum += texture(tex, vec2(X, Y - offset[i] * pixel.y)) * weight[i];
-        sum += texture(tex, vec2(X, Y + offset[i] * pixel.y)) * weight[i];
+    float g0, g1, g2;
+    g0 = 1.0 / (sqrt(2.0 * 3.14) * sigma);
+    g1 = exp(-0.5 / (sigma * sigma));
+    g2 = g1 * g1;
+    vec4 sum = texture(tex, vec2(X, Y)) * g0;
+    g0 *= g1;
+    g1 *= g2;
+    for (int i = 1; i < 9; i++) {
+        sum += texture(tex, vec2(X, Y - i * pixel.y)) * g0;
+        sum += texture(tex, vec2(X, Y + i * pixel.y)) * g0;
+        g0 *= g1;
+        g1 *= g2;
     }
 
     FragColor = sum;
 }
+
diff --git a/data/shaders/ssao.frag b/data/shaders/ssao.frag
index 7693590e9..5c0080ead 100644
--- a/data/shaders/ssao.frag
+++ b/data/shaders/ssao.frag
@@ -27,10 +27,10 @@ in vec2 uv;
 out float AO;
 
 const float sigma = 1.;
-const float tau = 2.;
+const float tau = 7.;
 const float beta = 0.0001;
 const float epsilon = .00001;
-const float radius = 1.;
+const float radius = 1.5;
 const float k = 1.;
 
 #define SAMPLES 16
diff --git a/src/graphics/render.cpp b/src/graphics/render.cpp
index 154be4eb9..42e7628c8 100644
--- a/src/graphics/render.cpp
+++ b/src/graphics/render.cpp
@@ -899,7 +899,7 @@ void IrrDriver::renderSSAO()
     m_post_processing->renderSSAO();
     // Blur it to reduce noise.
     m_post_processing->renderGaussian17TapBlur(irr_driver->getFBO(FBO_SSAO), irr_driver->getRenderTargetTexture(RTT_SSAO),
-        irr_driver->getFBO(FBO_TMP4), irr_driver->getRenderTargetTexture(RTT_TMP4), UserConfigParams::m_width, UserConfigParams::m_height);
+        irr_driver->getFBO(FBO_TMP4), irr_driver->getRenderTargetTexture(RTT_TMP4), UserConfigParams::m_width, UserConfigParams::m_height );
     glViewport(0, 0, UserConfigParams::m_width, UserConfigParams::m_height);
 }