pass rand to shaders

Signed-off-by: Ian Chen <[email protected]>

Author: iche033

ogre2/src/Ogre2ParticleNoiseListener.cc

@@ -17,6 +17,8 @@
 
 #include <string>
 
+#include <ignition/math/Rand.hh>
+
 #include "ignition/rendering/ogre2/Ogre2Includes.hh"
 #include "ignition/rendering/ogre2/Ogre2RenderTypes.hh"
 #include "ignition/rendering/ogre2/Ogre2Scene.hh"
@@ -85,6 +87,8 @@ void Ogre2ParticleNoiseListener::preRenderTargetUpdate(
           pass->getFragmentProgramParameters();
       psParams->setNamedConstant("particleStddev",
           static_cast<float>(particleStddev));
+      psParams->setNamedConstant("rnd",
+          static_cast<float>(ignition::math::Rand::DblUniform(0.0, 1.0)));
 
       // get particle scatter ratio value from particle emitter user data
       // and pass that to the shaders

ogre2/src/media/materials/programs/depth_camera_fs.glsl

@@ -39,7 +39,8 @@ uniform vec3 backgroundColor;
 
 uniform float particleStddev;
 uniform float particleScatterRatio;
-uniform float time;
+// rnd is a random number in the range of [0-1]
+uniform float rnd;
 
 float packFloat(vec4 color)
 {
@@ -105,11 +106,8 @@ void main()
   // by other objects in the camera view
   if (particle.x > 0 && particleDepth < fDepth)
   {
-    // time is used to add randomness. Limit value to [0-1]
-    float t = fract(time);
-
     // apply scatter effect so that only some of the smoke pixels are visible
-    float r = rand(inPs.uv0 + vec2(t, t));
+    float r = rand(inPs.uv0 + vec2(rnd, rnd));
     if (r < particleScatterRatio)
     {
       // set point to 3d pos of particle pixel
@@ -118,14 +116,14 @@ void main()
       vec3 particlePoint = vec3(-particleViewSpacePos.z, -particleViewSpacePos.x,
           particleViewSpacePos.y);
 
-      float rr = rand(inPs.uv0 + vec2(t, t)) - 0.5;
+      float rr = rand(inPs.uv0 + vec2(rnd, rnd)) - 0.5;
 
       // apply gaussian noise to particle point cloud data
       // With large particles, the range returned are all from the first large
       // particle. So add noise with some mean values so that all the points are
       // shifted further out. This gives depth readings beyond the first few
       // particles and avoid too many early returns
-      vec3 noise = gaussrand(inPs.uv0, vec3(t, t, t),
+      vec3 noise = gaussrand(inPs.uv0, vec3(rnd, rnd, rnd),
           particleStddev, rr*rr*particleStddev*0.5).xyz;
       float noiseLength = length(noise);
       float particlePointLength = length(particlePoint);

ogre2/src/media/materials/programs/gpu_rays_1st_pass_fs.glsl

@@ -38,7 +38,8 @@ uniform float max;
 
 uniform float particleStddev;
 uniform float particleScatterRatio;
-uniform float time;
+// rnd is a random number in the range of [0-1]
+uniform float rnd;
 
 // see gaussian_noise_fs.glsl for documentation on the rand and gaussrand
 // functions
@@ -91,24 +92,21 @@ void main()
   // check if need to apply scatter effect
   if (particle.x > 0.0 && particleDepth < fDepth)
   {
-    // time is used to add randomness. Limit value to [0-1]
-    float t = fract(time);
-
     // apply scatter effect so that only some of the smoke pixels are visible
-    float r = rand(inPs.uv0 + vec2(t, t));
+    float r = rand(inPs.uv0 + vec2(rnd, rnd));
     if (r < particleScatterRatio)
     {
       float pd = projectionParams.y / (particleDepth - projectionParams.x);
       vec3 point = inPs.cameraDir * pd;
 
-      float rr = rand(inPs.uv0 + vec2(t, t)) - 0.5;
+      float rr = rand(inPs.uv0 + vec2(rnd, rnd)) - 0.5;
 
       // apply gaussian noise to particle range data
       // With large particles, the range returned are all from the first large
       // particle. So add noise with some mean values so that all the points are
       // shifted further out. This gives depth readings beyond the first few
       // particles and avoid too many early returns
-      vec3 noise = gaussrand(inPs.uv0, vec3(t, t, t),
+      vec3 noise = gaussrand(inPs.uv0, vec3(rnd, rnd, rnd),
            particleStddev, rr*rr*particleStddev*0.5).xyz;
       float noiseLength = length(noise);