88 lines
2.5 KiB
Text
88 lines
2.5 KiB
Text
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varying vec3 q_tilde;
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//varying float u_tilde;
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varying vec3 inv_T_square_v;
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varying vec3 inv_T_square_e_c;
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varying vec4 e_clip;
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varying vec4 V_clip;
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varying vec3 h0;
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varying vec3 l0;
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varying vec3 h1;
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varying vec3 l1;
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varying vec4 a;
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void main()
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{
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// decompress the matrix T
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mat3 T;
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T[0] = gl_MultiTexCoord0.xyz;
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T[1].x = gl_MultiTexCoord0.y;
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T[1].yz = gl_MultiTexCoord1.xy;
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T[2].x = gl_MultiTexCoord0.z;
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T[2].y = gl_MultiTexCoord1.y;
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T[2].z = gl_MultiTexCoord1.z;
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// invert the matrix T
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mat3 inv_T;
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float inv_denom = 1.0/dot(T[0],cross(T[1],T[2]));
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inv_T[0] = inv_denom*cross(T[1],T[2]);
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inv_T[1] = inv_denom*cross(T[2],T[0]);
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inv_T[2] = inv_denom*cross(T[0],T[1]);
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// determine eye point in parameter space
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vec3 e = gl_ModelViewMatrixInverse[3].xyz;
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vec3 e_tilde = inv_T*(e - gl_Vertex.xyz);
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// compute helper
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float inv_e_square = 1.0/dot(e_tilde,e_tilde);
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// determine silhoutte center in parameter space
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vec3 m_tilde = inv_e_square*e_tilde;
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// determine radius of silhouette in parameter space
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float r = sqrt(1.0-inv_e_square);
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// compute vector x of length r orthogonal to e in parameter space
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vec3 x_tilde = vec3(0,0,0);
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if (abs(e_tilde[1]) > abs(e_tilde[0]))
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x_tilde[0] = 1.0;
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else
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x_tilde[1] = 1.0;
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x_tilde = r*normalize(cross(x_tilde,e_tilde));
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// compute vector y of length r orthogonal to x and e in parameter space
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vec3 y_tilde = r*normalize(cross(e_tilde,x_tilde));
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// compute the corner point in homogeneous object coordinates
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vec3 V_tilde = m_tilde+gl_MultiTexCoord2.x*x_tilde+gl_MultiTexCoord2.y*y_tilde;
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vec3 v_tilde = V_tilde - e_tilde;
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vec4 V;
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V.xyz = T*V_tilde+gl_Vertex.xyz;
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V.w = 1.0;
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q_tilde.xy = gl_MultiTexCoord2.xy;
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q_tilde.z = sqrt(inv_e_square);
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// compute vector from eye to vertex in eye space
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vec3 v = (gl_ModelViewMatrix*V).xyz;
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// compute components to compute normal in eye space
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inv_T_square_e_c = gl_NormalMatrix*(inv_T*e_tilde);
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inv_T_square_v = gl_NormalMatrix*(inv_T*v_tilde);
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// compute light source directions
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l0 = normalize(gl_LightSource[0].position.xyz);
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// compute half vectors in eye space
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v = -normalize(v);
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h0 = normalize(v+l0);
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l1 = normalize(vec3(gl_LightSource[1].position));
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h1 = normalize(v+l1);
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gl_FrontColor = gl_Color;
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e_clip = gl_ModelViewProjectionMatrix * gl_ModelViewMatrixInverse[3];
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V_clip = gl_ModelViewProjectionMatrix * V;
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gl_Position = V_clip;
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a = gl_FrontLightModelProduct.sceneColor;
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}
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