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

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Revision 3283 - (view) (download)

1 :	cchiw	3276
2 :			input real isoval = 0.5;
3 :			input real thick = 0.8;
4 :
5 :
6 :			field#2(3)[3,3] V = bspln3 ⊛ image("/Users/chariseechiw/diderot/charisee_dev/ertest/data/tball.nrrd");
7 :	cchiw	3283	field#0(3)[3,3,3] G=∇⊗V;
8 :	cchiw	3276
9 :
10 :
11 :			field#2(3)[3] hackRGB = bspln3 ⊛ image("/Users/chariseechiw/diderot/charisee_dev/data/const-curl3d.nrrd");
12 :			function vec3 color(vec3 x) = hackRGB(x);
13 :
14 :
15 :			vec3 cutVec = [-1,-0.03,0.02];
16 :			real cutPos = -1.5;
17 :
18 :			real refStep = 1;
19 :
20 :			// set camera, image, and rendering parameters
21 :			input vec3 camEye = [440.499, 66.673, 175.265];
22 :			input vec3 camAt = [69.6939, 103.067, 41.4651];
23 :			input vec3 camUp = [-0.0808311, 0.0976636, 0.991932];
24 :			input real camNearAtRel = -90;
25 :			input real camFarAtRel = 90;
26 :			input real camFOV = 17;
27 :			input int iresU = 520;
28 :			input int iresV = 370;
29 :			input real phongKa = 0.3;
30 :			input real phongKd = 0.7;
31 :			input real rayStep = 0.4;
32 :			input vec3 lightVsp = [-2.0, -2.5, -8.0];
33 :
34 :			// (boilerplate) computation of camera and light info
35 :			real camDist = |camAt - camEye|;
36 :			real camNear = camNearAtRel + camDist;
37 :			real camFar = camFarAtRel + camDist;
38 :			vec3 camN = normalize(camAt - camEye); // away from eye
39 :			vec3 camU = normalize(camN × camUp); // right
40 :			vec3 camV = camN × camU; // down
41 :			real camVmax = tan(camFOV*π/360)*camDist;
42 :			real camUmax = camVmax*iresU/iresV;
43 :			vec3 light = transpose([camU,camV,camN])•normalize(lightVsp);
44 :
45 :			function real alpha(real v, real g) = 1.0 if (v > 0) else clamp(0, 1, 1.3*(1 - |v|/(g*thick)));
46 :
47 :			strand raycast(int ui, int vi) {
48 :			real rayU = lerp(-camUmax, camUmax, -0.5, ui, iresU-0.5);
49 :			real rayV = lerp(-camVmax, camVmax, -0.5, vi, iresV-0.5);
50 :			real rayN = camNear;
51 :			vec3 rayVec = (camDist*camN + rayU*camU + rayV*camV)/camDist;
52 :			real transp = 1;
53 :			vec3 rgb = [0, 0, 0];
54 :			output vec4 rgba = [0, 0, 0, 0];
55 :
56 :			update {
57 :			vec3 x = camEye + rayN*rayVec;
58 :			if (inside(x,V) && (x - camAt)•normalize(cutVec) > cutPos) {
59 :			real val = 0;
60 :			vec3 grad = [0,0,0];
61 :	cchiw	3283
62 :
63 :			real m=|V(x)|;
64 :			tensor[3,3,3] g=G(x);
65 :			tensor[3] t1=(1/2)*(V(x):g+g:V(x))/m;
66 :	cchiw	3276
67 :	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]];
68 :			tensor [3,3] E = V(x) - trace(V(x))*identity[3]/3;
69 :			tensor[3,3,3] t3= g-t2⊗identity[3]/3;
70 :			real t4=|E|;
71 :			tensor [3] t5=(1/2)*(t3:E +E:t3)/(E:E);
72 :	cchiw	3276
73 :	cchiw	3283	val=sqrt(3.0/2.0)*t4/m - isoval;
74 :
75 :			real t8=sqrt(3.0/2.0);
76 :			vec3 t6 =(m*t5);
77 :			vec3 t7 = (t4*t1);
78 :			grad =t8*(t6- t7)/(m*m);
79 :	cchiw	3276
80 :			real a = alpha(val, |grad|);
81 :			if (a > 0) {
82 :			a = 1 - pow(1-a, rayStep);
83 :			real depth = lerp(1.1, 0.8, camNear, rayN, camFar);
84 :			real shade = max(0, normalize(grad)•light);
85 :			vec3 thisrgb = (phongKa + phongKd*shade)*color(x);
86 :			if ((x - camAt)•normalize(cutVec) < cutPos + 1.1*rayStep) {
87 :			thisrgb = phongKd*color(x);
88 :			}
89 :			rgb += transp*a*depth*thisrgb;
90 :			transp *= 1 - a;
91 :			}
92 :			}
93 :			if (transp < 0.01) { // early ray termination
94 :			transp = 0;
95 :			stabilize;
96 :			}
97 :			if (rayN > camFar) {
98 :			stabilize;
99 :			}
100 :			rayN = rayN + rayStep;
101 :			}
102 :			stabilize {
103 :			real a = 1-transp;
104 :			if (a > 0) rgba = [rgb[0]/a, rgb[1]/a, rgb[2]/a, a];
105 :			}
106 :			}
107 :			initially [ raycast(ui, vi) | vi in 0..iresV-1, ui in 0..iresU-1 ];

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