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-rw-r--r--graphics/asymptote/webgl/fragment.glsl95
1 files changed, 95 insertions, 0 deletions
diff --git a/graphics/asymptote/webgl/fragment.glsl b/graphics/asymptote/webgl/fragment.glsl
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+++ b/graphics/asymptote/webgl/fragment.glsl
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+#ifdef NORMAL
+#ifndef ORTHOGRAPHIC
+varying vec3 ViewPosition;
+#endif
+varying vec3 Normal;
+varying vec4 diffuse;
+varying vec3 specular;
+varying float roughness,metallic,fresnel0;
+
+float Roughness2;
+vec3 normal;
+
+struct Light {
+ vec3 direction;
+ vec3 color;
+};
+
+uniform Light Lights[Nlights];
+
+float NDF_TRG(vec3 h)
+{
+ float ndoth=max(dot(normal,h),0.0);
+ float alpha2=Roughness2*Roughness2;
+ float denom=ndoth*ndoth*(alpha2-1.0)+1.0;
+ return denom != 0.0 ? alpha2/(denom*denom) : 0.0;
+}
+
+float GGX_Geom(vec3 v)
+{
+ float ndotv=max(dot(v,normal),0.0);
+ float ap=1.0+Roughness2;
+ float k=0.125*ap*ap;
+ return ndotv/((ndotv*(1.0-k))+k);
+}
+
+float Geom(vec3 v, vec3 l)
+{
+ return GGX_Geom(v)*GGX_Geom(l);
+}
+
+float Fresnel(vec3 h, vec3 v, float fresnel0)
+{
+ float a=1.0-max(dot(h,v),0.0);
+ float b=a*a;
+ return fresnel0+(1.0-fresnel0)*b*b*a;
+}
+
+// physical based shading using UE4 model.
+vec3 BRDF(vec3 viewDirection, vec3 lightDirection)
+{
+ vec3 lambertian=diffuse.rgb;
+ vec3 h=normalize(lightDirection+viewDirection);
+
+ float omegain=max(dot(viewDirection,normal),0.0);
+ float omegali=max(dot(lightDirection,normal),0.0);
+
+ float D=NDF_TRG(h);
+ float G=Geom(viewDirection,lightDirection);
+ float F=Fresnel(h,viewDirection,fresnel0);
+
+ float denom=4.0*omegain*omegali;
+ float rawReflectance=denom > 0.0 ? (D*G)/denom : 0.0;
+
+ vec3 dielectric=mix(lambertian,rawReflectance*specular,F);
+ vec3 metal=rawReflectance*diffuse.rgb;
+
+ return mix(dielectric,metal,metallic);
+}
+#endif
+varying vec4 emissive;
+
+void main(void)
+{
+#if defined(NORMAL) && nlights > 0
+ normal=normalize(Normal);
+ normal=gl_FrontFacing ? normal : -normal;
+#ifdef ORTHOGRAPHIC
+ vec3 viewDir=vec3(0.0,0.0,1.0);
+#else
+ vec3 viewDir=-normalize(ViewPosition);
+#endif
+ Roughness2=roughness*roughness;
+ vec3 color=emissive.rgb;
+ for(int i=0; i < nlights; ++i) {
+ Light Li=Lights[i];
+ vec3 L=Li.direction;
+ float cosTheta=max(dot(normal,L),0.0);
+ vec3 radiance=cosTheta*Li.color;
+ color += BRDF(viewDir,L)*radiance;
+ }
+ gl_FragColor=vec4(color,diffuse.a);
+#else
+ gl_FragColor=emissive;
+#endif
+}