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elene@25
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1 varying vec3 pt;
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elene@25
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2
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3 uniform sampler3D tex;
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4 uniform float tmin;
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5 uniform float tmax;
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6 uniform vec3 res;
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7
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8 float transfer(float x, float tmin, float tmax)
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9 {
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10 float dt = 0.25 * (tmax - tmin);
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11 return smoothstep(tmin - dt, tmin + dt, x) *
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12 (1.0 - smoothstep(tmax - dt, tmax + dt, x));
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13 }
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14
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15 vec3 calc_normal(vec3 p, float texel)
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16 {
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17 vec3 offs = 1.0 / res;
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18
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19 float dfdx = texture3D(tex, p + vec3(offs.x, 0.0, 0.0)).x - texel;
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20 float dfdy = texture3D(tex, p + vec3(0.0, offs.y, 0.0)).x - texel;
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21 float dfdz = texture3D(tex, p + vec3(0.0, 0.0, offs.z)).x - texel;
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22
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elene@30
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23 return -normalize(vec3(dfdx, dfdy, dfdz));
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24 }
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elene@25
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25
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elene@25
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26 void main()
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27 {
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28 const vec3 ldir = vec3(-1.0, 1.0, 2.0);
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29
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30 if(max(pt.x, max(pt.y, pt.z)) > 1.0 || min(pt.x, min(pt.y, pt.z)) < 0.0)
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31 discard;
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32
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33 float texel = texture3D(tex, pt).x;
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34 float val = transfer(texel, tmin, tmax);
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35
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elene@30
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36 vec3 normal = gl_NormalMatrix * calc_normal(pt, texel);
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37 float ndotl = max(dot(normalize(ldir), normal), 0.0);
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38
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39 gl_FragColor = vec4(ndotl, ndotl, ndotl, val);
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40 }
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