Okay, after hours after hours of debugging and research only pure luck gave me
the final hint:
Non-uniform flow control and, as a result, undefined behavior.
Apperantly one cannot access texture coordinates savely, if the point of access
in the code is not uniform, e.g. after an if-statement, which was exactly the
point in my shader code:
I accessed the toonTex in the if(front) condition and, even bigger, after the
condition block I accessed the texture0. These access was not uniform and
therefore I was pure coincidence that it worked on my graphics card.
I changed my shader like this (now more unused vars are generated each turn,
but it works!):
Code:
#version 120
#define NUM_LIGHTS 8
uniform sampler2D texture0;
uniform sampler2D toonTex;
uniform float osg_FrameTime;
uniform bool tex;
varying vec3 normalModelView;
varying vec4 vertexModelView;
vec4 calculateLightFromLightSource(int lightIndex, bool front){
vec3 lightDir;
vec3 eye = normalize(-vertexModelView.xyz);
vec4 curLightPos = gl_LightSource[lightIndex].position;
//curLightPos.z = sin(10*osg_FrameTime)*4+curLightPos.z;
lightDir = normalize(curLightPos.xyz - vertexModelView.xyz);
float dist = distance( gl_LightSource[lightIndex].position,
vertexModelView );
float attenuation = 1.0 /
(gl_LightSource[lightIndex].constantAttenuation
+ gl_LightSource[lightIndex].linearAttenuation
* dist
+
gl_LightSource[lightIndex].quadraticAttenuation * dist * dist);
float z = length(vertexModelView);
vec4 color;
vec3 n = normalize(normalModelView);
vec3 nBack = normalize(-normalModelView);
float intensity = dot(n,lightDir); //NdotL, Lambert
float intensityBack = dot(nBack,lightDir); //NdotL, Lambert
//-Phong Modell
vec3 reflected = normalize(reflect( -lightDir, n));
float specular = pow(max(dot(reflected, eye), 0.0),
gl_FrontMaterial.shininess);
vec3 reflectedBack = normalize(reflect( -lightDir, nBack));
float specularBack = pow(max(dot(reflectedBack, eye), 0.0),
gl_BackMaterial.shininess);
//Toon-Shading
//2D Toon
http://www.cs.rpi.edu/~cutler/classes/advancedgraphics/S12/final_projects/hutchins_kim.pdf
vec4 toonColor = texture2D(toonTex,vec2(intensity,specular));
vec4 toonColorBack =
texture2D(toonTex,vec2(intensityBack,specularBack));
if(front){
color += gl_FrontMaterial.ambient *
gl_LightSource[lightIndex].ambient[lightIndex];
if(intensity > 0.0){
color += gl_FrontMaterial.diffuse *
gl_LightSource[lightIndex].diffuse * intensity * attenuation ;
color += gl_FrontMaterial.specular *
gl_LightSource[lightIndex].specular * specular *attenuation ;
}
return color * toonColor;
} else {//back
color += gl_BackMaterial.ambient *
gl_LightSource[lightIndex].ambient[lightIndex];
if(intensity > 0.0){
color += gl_BackMaterial.diffuse *
gl_LightSource[lightIndex].diffuse * intensityBack * attenuation ;
color += gl_BackMaterial.specular *
gl_LightSource[lightIndex].specular * specularBack *attenuation ;
}
return color * toonColorBack;
}
}
void main(void) {
vec4 color = vec4(0.0);
bool front = true;
//non-uniform-flow error correction
//happens sometome (mostyl on NVIDIA)
//see more here:
http://www.opengl.org/wiki/GLSL_Sampler#Non-uniform_flow_control
//and here:
http://gamedev.stackexchange.com/questions/32543/glsl-if-else-statement-unexpected-behaviour
vec4 texColor = texture2D(texture0,gl_TexCoord[0].xy);
if(!gl_FrontFacing)
front = false;
for(int i = 0; i< NUM_LIGHTS; i++){
color += calculateLightFromLightSource(i,front);
}
if(tex)
gl_FragColor =color * texColor;
else
gl_FragColor = color;
}
The final info I got from here:
http://gamedev.stackexchange.com/questions/32543/glsl-if-else-statement-unexpected-behaviour
and here:
http://www.opengl.org/wiki/GLSL_Sampler#Non-uniform_flow_control
Thank you!
Cheers,
Fitz
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=59738#59738
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