FakeCaustics - 图1

    1. // Found this on GLSL sandbox. I really liked it, changed a few things and made it tileable.
    2. // by David Hoskins.
    3. // Water turbulence effect by joltz0r 2013-07-04, improved 2013-07-07
    4. // Updated 1/4/2020 by Saul Espinosa for Redshift 3D
    5. // This file is licensed under Apache 2.0 license
    8. // Redefine below to see the tiling...
    9. //#define SHOW_TILING
    11. #define TAU 6.28318530718
    14. shader FakeCaustics
    15. [[  string help = "generates a psuedo caustic like noise pattern",
    16.     string label = "Fake Caustics" ]]
    17. ( 
    19.     point Po = P,
    20.     float Time = 0
    21.     [[
    22.     float min = 0, float max = 100
    23.     ]],
    24.     int iterations = 5
    25.     [[
    26.     int min = 0, int max = 20
    27.     ]],
    28.     output color Out = 0,
    30.     ) 
    31. {
    32.     float tt = Time * .5+23.0;
    33.     // uv should be the 0-1 uv of texture...
    34.     vector uv = Po;
    36.     vector p = mod(uv*TAU*2.0, TAU)-250.0;
    38.     // vector p = mod(uv*TAU, TAU)-250.0;
    40.     vector i = vector(p);
    41.     float c = 1.0;
    42.     float inten = .005;
    44.     for (int n = 0; n < iterations; n++) 
    45.     {
    46.         float t = tt * (1.0 - (3.5 / float(n+1)));
    47.         i = p + vector(cos(t - i[0]) + sin(t + i[1]), sin(t - i[1]) + cos(t + i[0]),0);
    48.         c += 1.0/length(vector(p[0] / (sin(i[0]+t)/inten),p[1] / (cos(i[1]+t)/inten),0));
    49.     }
    50.     c /= float(iterations);
    51.     c = 1.17-pow(c, 1.4);
    52.     vector colour = vector(pow(abs(c), 8.0));
    53.     colour = clamp(colour + vector(0.0, 0.35, 0.5), 0.0, 1.0);
    55. /*
    56.     #ifdef SHOW_TILING
    57.     // Flash tile borders...
    58.     vec2 pixel = 2.0 / iResolution.xy;
    59.     uv *= 2.0;
    61.     float f = floor(mod(iTime*.5, 2.0));     // Flash value.
    62.     vec2 first = step(pixel, uv) * f;               // Rule out first screen pixels and flash.
    63.     uv  = step(fract(uv), pixel);                // Add one line of pixels per tile.
    64.     colour = mix(colour, vec3(1.0, 1.0, 0.0), (uv.x + uv.y) * first.x * first.y); // Yellow line
    66. */
    67.     Out = vector(colour);
    68.     Out = pow(Out,2.2);
    69. }