113 lines
3.1 KiB
GLSL
113 lines
3.1 KiB
GLSL
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uniform sampler3D velocityX;
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uniform sampler3D velocityY;
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uniform sampler3D velocityZ;
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uniform float displaySize = 1.0;
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uniform float slicePosition;
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uniform int sliceAxis; /* -1 is no slice, 0 is X, 1 is Y, 2 is Z. */
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flat out vec4 finalColor;
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const vec3 corners[4] = vec3[4](vec3(0.0, 0.2, -0.5),
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vec3(-0.2 * 0.866, -0.2 * 0.5, -0.5),
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vec3(0.2 * 0.866, -0.2 * 0.5, -0.5),
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vec3(0.0, 0.0, 0.5));
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const int indices[12] = int[12](0, 1, 1, 2, 2, 0, 0, 3, 1, 3, 2, 3);
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/* Straight Port from BKE_defvert_weight_to_rgb()
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* TODO port this to a color ramp. */
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vec3 weight_to_color(float weight)
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{
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vec3 r_rgb = vec3(0.0);
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float blend = ((weight / 2.0) + 0.5);
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if (weight <= 0.25) { /* blue->cyan */
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r_rgb.g = blend * weight * 4.0;
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r_rgb.b = blend;
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}
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else if (weight <= 0.50) { /* cyan->green */
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r_rgb.g = blend;
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r_rgb.b = blend * (1.0 - ((weight - 0.25) * 4.0));
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}
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else if (weight <= 0.75) { /* green->yellow */
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r_rgb.r = blend * ((weight - 0.50) * 4.0);
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r_rgb.g = blend;
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}
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else if (weight <= 1.0) { /* yellow->red */
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r_rgb.r = blend;
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r_rgb.g = blend * (1.0 - ((weight - 0.75) * 4.0));
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}
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else {
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/* exceptional value, unclamped or nan,
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* avoid uninitialized memory use */
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r_rgb = vec3(1.0, 0.0, 1.0);
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}
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return r_rgb;
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}
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mat3 rotation_from_vector(vec3 v)
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{
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/* Add epsilon to avoid NaN. */
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vec3 N = normalize(v + 1e-8);
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vec3 UpVector = abs(N.z) < 0.99999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);
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vec3 T = normalize(cross(UpVector, N));
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vec3 B = cross(N, T);
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return mat3(T, B, N);
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}
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void main()
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{
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#ifdef USE_NEEDLE
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int cell = gl_VertexID / 12;
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#else
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int cell = gl_VertexID / 2;
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#endif
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ivec3 volume_size = textureSize(velocityX, 0);
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float voxel_size = 1.0 / float(max(max(volume_size.x, volume_size.y), volume_size.z));
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ivec3 cell_ofs = ivec3(0);
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ivec3 cell_div = volume_size;
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if (sliceAxis == 0) {
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cell_ofs.x = int(slicePosition * float(volume_size.x));
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cell_div.x = 1;
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}
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else if (sliceAxis == 1) {
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cell_ofs.y = int(slicePosition * float(volume_size.y));
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cell_div.y = 1;
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}
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else if (sliceAxis == 2) {
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cell_ofs.z = int(slicePosition * float(volume_size.z));
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cell_div.z = 1;
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}
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ivec3 cell_co;
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cell_co.x = cell % cell_div.x;
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cell_co.y = (cell / cell_div.x) % cell_div.y;
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cell_co.z = cell / (cell_div.x * cell_div.y);
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cell_co += cell_ofs;
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vec3 pos = (vec3(cell_co) + 0.5) / vec3(volume_size);
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pos = pos * 2.0 - 1.0;
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vec3 velocity;
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velocity.x = texelFetch(velocityX, cell_co, 0).r;
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velocity.y = texelFetch(velocityY, cell_co, 0).r;
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velocity.z = texelFetch(velocityZ, cell_co, 0).r;
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finalColor = vec4(weight_to_color(length(velocity)), 1.0);
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#ifdef USE_NEEDLE
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mat3 rot_mat = rotation_from_vector(velocity);
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vec3 rotated_pos = rot_mat * corners[indices[gl_VertexID % 12]];
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pos += rotated_pos * length(velocity) * displaySize * voxel_size;
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#else
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pos += (((gl_VertexID % 2) == 1) ? velocity : vec3(0.0)) * displaySize * voxel_size;
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#endif
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vec3 world_pos = point_object_to_world(pos);
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gl_Position = point_world_to_ndc(world_pos);
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}
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