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Diffstat (limited to 'src/extras/shaders/es2/gooch.frag')
-rw-r--r-- | src/extras/shaders/es2/gooch.frag | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/src/extras/shaders/es2/gooch.frag b/src/extras/shaders/es2/gooch.frag new file mode 100644 index 000000000..622aaf0b4 --- /dev/null +++ b/src/extras/shaders/es2/gooch.frag @@ -0,0 +1,56 @@ +#define FP highp + +// TODO: Replace with a struct +uniform FP vec3 kd; // Diffuse reflectivity +uniform FP vec3 ks; // Specular reflectivity +uniform FP vec3 kblue; // Cool color +uniform FP vec3 kyellow; // Warm color +uniform FP float alpha; // Fraction of diffuse added to kblue +uniform FP float beta; // Fraction of diffuse added to kyellow +uniform FP float shininess; // Specular shininess factor + +uniform FP vec3 eyePosition; + +varying FP vec3 worldPosition; +varying FP vec3 worldNormal; + +#pragma include light.inc.frag + +FP vec3 goochModel( const in FP vec3 pos, const in FP vec3 n ) +{ + // Based upon the original Gooch lighting model paper at: + // http://www.cs.northwestern.edu/~ago820/SIG98/abstract.html + + // Calculate kcool and kwarm from equation (3) + FP vec3 kcool = clamp(kblue + alpha * kd, 0.0, 1.0); + FP vec3 kwarm = clamp(kyellow + beta * kd, 0.0, 1.0); + + // Calculate the vector from the light to the fragment + FP vec3 s = normalize( vec3( lights[0].position ) - pos ); + + // Calculate the cos theta factor mapped onto the range [0,1] + FP float sDotNFactor = ( 1.0 + dot( s, n ) ) / 2.0; + + // Calculate the tone by blending the kcool and kwarm contributions + // as per equation (2) + FP vec3 intensity = mix( kcool, kwarm, sDotNFactor ); + + // Calculate the vector from the fragment to the eye position + FP vec3 v = normalize( eyePosition - pos ); + + // Reflect the light beam using the normal at this fragment + FP vec3 r = reflect( -s, n ); + + // Calculate the specular component + FP float specular = 0.0; + if ( dot( s, n ) > 0.0 ) + specular = pow( max( dot( r, v ), 0.0 ), shininess ); + + // Sum the blended tone and specular highlight + return intensity + ks * specular; +} + +void main() +{ + gl_FragColor = vec4( goochModel( worldPosition, normalize( worldNormal ) ), 1.0 ); +} |