Matcap shader and modelview matrix

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#1

I’m trying to implement matcap shader from this reference clicktorelease.com/blog/crea … ing-shader
I copied and modified litSolid shader and changed the cubemap, so it map to the sphere on emissive texture( because env unit is cube). Here is modification of fragment shader:

#ifdef ENVCUBEMAP
    vec3 r =reflect(vReflectionVec, normal);
    float m = 2. * sqrt( pow( r.x, 2. ) + pow( r.y, 2. ) + pow( r.z + 1., 2. ) );
    vec2 vN = r.xy / m + .5;
    finalColor += cMatEnvMapColor * texture2D( sEmissiveMap, vN ).rgb;
#endif

I got some nice results but it isn’t still what it should be - the matcap’s reflections are distorted. I suppose this is this because

vReflectionVec =  worldPos-cCameraPos;

isn’t equivalent to

e = normalize( vec3( modelViewMatrix * vec4( position, 1.0 ) ) );

in Urho’s shader defines I can see cViewProj and cModel matrixes, but how can I get modelViewMatrix?

#2

Ok, it’s working, I forgot to normalize from eye vector :blush:

1086×828

#3

[quote=“szamq”]Ok, it’s working, I forgot to normalize from eye vector :blush:

1086×828

Very nice.

#4

Well done :slight_smile:
Do you plan to disclose full code or send a pull request?
I think we need more shaders.

#5

I’m not sure how to integrate this. Because the environment sphere can’t be set to env texture unit because it is cubemap, so I used emissive texture for that.
Just modify ENVCUBEMAP defines in LitSolid shader like below and set your matcap texture google.pl/search?q=matcap to emmisive texture unit. Then you can use DiffEnvCube.xml technique in editor to see the effect.

Here are modifications.
vertex shader

#ifdef ENVCUBEMAP vReflectionVec = normalize(worldPos-cCameraPos); #endif
fragment shader

      #ifdef ENVCUBEMAP
            vec3 r =reflect(vReflectionVec, normal);
            float m = 2. * sqrt( pow( r.x, 2. ) + pow( r.y, 2. ) + pow( r.z + 1., 2. ) );
            vec2 vN = r.xy / m + .5;
            finalColor += cMatEnvMapColor * texture2D( sEmissiveMap, vN ).rgb;
        #endif
LitSphere/MatCap texture maps
#6

Thanks a lot, will try this today. :wink:

#7

Yeah it works alright. Thanks for sharing szamq. I spent a few hours trying to figure out to get this into its own technique. The exercise was just what I needed to starting to understanding how the render passes work. I think I can package it up so its easier to use. It will take me quite a while longer to get all of the useful permutations figured out.

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That is a glossy green ninja alright…