4 out float smoothness_x, smoothness_y;
5 const float eps_sq = 0.001 * 0.001;
7 uniform sampler2D flow_tex, diff_flow_tex;
9 // Relative weighting of smoothness term.
12 uniform bool zero_diff_flow;
14 // This must be a macro, since the offset needs to be a constant expression.
15 #define get_flow(x_offs, y_offs) \
16 (textureOffset(flow_tex, tc, ivec2((x_offs), (y_offs))).xy + \
17 textureOffset(diff_flow_tex, tc, ivec2((x_offs), (y_offs))).xy)
19 #define get_flow_no_diff(x_offs, y_offs) \
20 textureOffset(flow_tex, tc, ivec2((x_offs), (y_offs))).xy
22 float diffusivity(float u_x, float u_y, float v_x, float v_y)
24 return alpha * inversesqrt(u_x * u_x + u_y * u_y + v_x * v_x + v_y * v_y + eps_sq);
29 float g, g_right, g_up;
32 // These are shared between some of the diffusivities.
33 vec2 flow_0_0 = get_flow_no_diff(0, 0);
34 vec2 flow_1_1 = get_flow_no_diff(1, 1);
36 // Find diffusivity (g) for this pixel, using central differences.
38 vec2 uv_x = get_flow_no_diff(1, 0) - get_flow_no_diff(-1, 0);
39 vec2 uv_y = get_flow_no_diff(0, 1) - get_flow_no_diff( 0, -1);
40 g = diffusivity(uv_x.x, uv_y.x, uv_x.y, uv_y.y);
43 // Now find diffusivity for the pixel to the right.
45 vec2 uv_x = get_flow_no_diff(2, 0) - flow_0_0;
46 vec2 uv_y = flow_1_1 - get_flow_no_diff( 1, -1);
47 g_right = diffusivity(uv_x.x, uv_y.x, uv_x.y, uv_y.y);
52 vec2 uv_x = flow_1_1 - get_flow_no_diff(-1, 1);
53 vec2 uv_y = get_flow_no_diff(0, 2) - flow_0_0;
54 g_up = diffusivity(uv_x.x, uv_y.x, uv_x.y, uv_y.y);
57 // These are shared between some of the diffusivities.
58 vec2 flow_0_0 = get_flow(0, 0);
59 vec2 flow_1_1 = get_flow(1, 1);
61 // Find diffusivity (g) for this pixel, using central differences.
63 vec2 uv_x = get_flow(1, 0) - get_flow(-1, 0);
64 vec2 uv_y = get_flow(0, 1) - get_flow( 0, -1);
65 g = diffusivity(uv_x.x, uv_y.x, uv_x.y, uv_y.y);
68 // Now find diffusivity for the pixel to the right.
70 vec2 uv_x = get_flow(2, 0) - flow_0_0;
71 vec2 uv_y = flow_1_1 - get_flow( 1, -1);
72 g_right = diffusivity(uv_x.x, uv_y.x, uv_x.y, uv_y.y);
77 vec2 uv_x = flow_1_1 - get_flow(-1, 1);
78 vec2 uv_y = get_flow(0, 2) - flow_0_0;
79 g_up = diffusivity(uv_x.x, uv_y.x, uv_x.y, uv_y.y);
83 smoothness_x = 0.5 * (g + g_right);
84 smoothness_y = 0.5 * (g + g_up);