Annotation of /branches/charisee_dev/examples/dti/dti-vr-byhand.diderot

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Revision 3313 - (view) (download)

1 :	cchiw	3276	input real isoval = 0.5;
2 :			input real thick = 0.8;
3 :	cchiw	3313	field#2(3)[3,3] V = bspln3 ⊛ image("tball.nrrd");
4 :	cchiw	3283	field#0(3)[3,3,3] G=∇⊗V;
5 :	cchiw	3313	field#2(3)[3] hackRGB = bspln3 ⊛ image("const-curl3d.nrrd");
6 :	cchiw	3276	function vec3 color(vec3 x) = hackRGB(x);
7 :			vec3 cutVec = [-1,-0.03,0.02];
8 :			real cutPos = -1.5;
9 :			real refStep = 1;
10 :			input vec3 camEye = [440.499, 66.673, 175.265];
11 :			input vec3 camAt = [69.6939, 103.067, 41.4651];
12 :			input vec3 camUp = [-0.0808311, 0.0976636, 0.991932];
13 :			input real camNearAtRel = -90;
14 :			input real camFarAtRel = 90;
15 :			input real camFOV = 17;
16 :			input int iresU = 520;
17 :			input int iresV = 370;
18 :			input real phongKa = 0.3;
19 :			input real phongKd = 0.7;
20 :			input real rayStep = 0.4;
21 :			input vec3 lightVsp = [-2.0, -2.5, -8.0];
22 :			real camDist = |camAt - camEye|;
23 :			real camNear = camNearAtRel + camDist;
24 :			real camFar = camFarAtRel + camDist;
25 :			vec3 camN = normalize(camAt - camEye); // away from eye
26 :			vec3 camU = normalize(camN × camUp); // right
27 :			vec3 camV = camN × camU; // down
28 :			real camVmax = tan(camFOV*π/360)*camDist;
29 :			real camUmax = camVmax*iresU/iresV;
30 :			vec3 light = transpose([camU,camV,camN])•normalize(lightVsp);
31 :
32 :			function real alpha(real v, real g) = 1.0 if (v > 0) else clamp(0, 1, 1.3*(1 - |v|/(g*thick)));
33 :
34 :			strand raycast(int ui, int vi) {
35 :			real rayU = lerp(-camUmax, camUmax, -0.5, ui, iresU-0.5);
36 :			real rayV = lerp(-camVmax, camVmax, -0.5, vi, iresV-0.5);
37 :			real rayN = camNear;
38 :			vec3 rayVec = (camDist*camN + rayU*camU + rayV*camV)/camDist;
39 :			real transp = 1;
40 :			vec3 rgb = [0, 0, 0];
41 :			output vec4 rgba = [0, 0, 0, 0];
42 :
43 :			update {
44 :			vec3 x = camEye + rayN*rayVec;
45 :			if (inside(x,V) && (x - camAt)•normalize(cutVec) > cutPos) {
46 :			real val = 0;
47 :			vec3 grad = [0,0,0];
48 :	cchiw	3283	real m=|V(x)|;
49 :			tensor[3,3,3] g=G(x);
50 :	cchiw	3313	tensor[3] t1=(1/2)*(V(x):g+g:V(x))/m;
51 :	cchiw	3283	vec3 t2=[g[0,0,0]+g[0,1,1]+g[0,2,2],g[1,0,0]+g[1,1,1]+g[1,2,2],g[2,0,0]+g[2,1,1]+g[2,2,2]];
52 :			tensor [3,3] E = V(x) - trace(V(x))*identity[3]/3;
53 :	cchiw	3307	tensor[3,3,3] t3= g-t2⊗identity[3]/3;
54 :	cchiw	3283	real t4=|E|;
55 :	cchiw	3313	tensor [3] t5=(1/2)*(t3:E +E:t3)/(E:E);
56 :			val=sqrt(3.0/2.0)*t4/m - isoval;
57 :			vec3 t6 =m*t5;
58 :			vec3 t7 = t4*t1;
59 :			grad =sqrt(3.0/2.0)*(t6- t7)/(m*m);
60 :	cchiw	3276	real a = alpha(val, |grad|);
61 :			if (a > 0) {
62 :			a = 1 - pow(1-a, rayStep);
63 :			real depth = lerp(1.1, 0.8, camNear, rayN, camFar);
64 :			real shade = max(0, normalize(grad)•light);
65 :			vec3 thisrgb = (phongKa + phongKd*shade)*color(x);
66 :			if ((x - camAt)•normalize(cutVec) < cutPos + 1.1*rayStep) {
67 :			thisrgb = phongKd*color(x);
68 :			}
69 :			rgb += transp*a*depth*thisrgb;
70 :			transp *= 1 - a;
71 :			}
72 :			}
73 :			if (transp < 0.01) { // early ray termination
74 :			transp = 0;
75 :			stabilize;
76 :			}
77 :			if (rayN > camFar) {
78 :			stabilize;
79 :			}
80 :			rayN = rayN + rayStep;
81 :			}
82 :			stabilize {
83 :			real a = 1-transp;
84 :			if (a > 0) rgba = [rgb[0]/a, rgb[1]/a, rgb[2]/a, a];
85 :			}
86 :			}
87 :			initially [ raycast(ui, vi) | vi in 0..iresV-1, ui in 0..iresU-1 ];

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