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zydeco / 5a717fe

Experiment in graphics programming, C++, OpenGL, simulation techniques.

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1008 Dec 2023 15:215a717feFractal renderer update for articleJosh Stockin188G

Blob @ zydeco / include / render / shaders / fractal.cs.glsl

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1R""(
2
3#version 460 core
4
5layout (local_size_x = 32, local_size_y = 32, local_size_z = 1) in;
6
7
8layout(rgba32f, binding = 0) uniform image2D texture0;
9uniform ivec2 screensize;
10uniform dvec2 offset;
11uniform double zoom;
12uniform float z;
13uniform float discard_threshold;
14uniform int current_iteration;
15uniform int it_steps;
16uniform bool enable_interlacing;
17uniform int interlace_layer;
18
19
20const int ADAM7_MATRIX[8][8] = {
21 {1, 6, 4, 6, 2, 6, 4, 6},
22 {7, 7, 7, 7, 7, 7, 7, 7},
23 {5, 6, 5, 6, 5, 6, 5, 6},
24 {7, 7, 7, 7, 7, 7, 7, 7},
25 {3, 6, 4, 6, 3, 6, 4, 6},
26 {7, 7, 7, 7, 7, 7, 7, 7},
27 {5, 6, 5, 6, 5, 6, 5, 6},
28 {7, 7, 7, 7, 7, 7, 7, 7},
29};
30
31
32dvec2 screenSpaceToGraphSpace(dvec2 coord)
33{
34 dvec2 dscreensize = dvec2(screensize);
35 double aspectratio = dscreensize.x/dscreensize.y;
36 return (((coord - dscreensize/2) / dscreensize * zoom) - (offset / dscreensize))*dvec2(aspectratio, 1.0);
37}
38
39void main()
40{
41 ivec2 texelCoord = ivec2(gl_GlobalInvocationID.xy);
42
43 vec4 currentValue;
44
45 dvec2 c = screenSpaceToGraphSpace(vec2(texelCoord));
46 c.y = -c.y;
47 if (current_iteration == 0 && interlace_layer == 1)
48 {
49 currentValue = vec4(0.5, c.x, c.y, 1.0);
50 }
51 else
52 {
53 currentValue = imageLoad(texture0, texelCoord);
54 }
55
56
57 bool do_compute = true;
58 if (enable_interlacing)
59 {
60 do_compute = ADAM7_MATRIX[gl_LocalInvocationID.y % 8][gl_LocalInvocationID.x % 8] == interlace_layer;
61 }
62 if (do_compute)
63 {
64 if (abs(currentValue.x) < 0.6)
65 {
66 double x = c.x;//abs(c.x);
67 double y = c.y;//abs(c.y);
68 double x2 = x*x;
69 double y2 = y*y;
70
71 for (int i = 1; i < it_steps; i++)
72 {
73 y = 2.*x*y + c.y;
74 //y = 2.*abs(x*y+z) + c.y - 2.*abs(z);
75 x = x2 - y2 + c.x;
76 x2 = x*x;
77 y2 = y*y;
78 if ((x2 + y2) > discard_threshold)
79 {
80 currentValue.x = current_iteration + i;
81 break;
82 }
83 }
84 currentValue.yz = vec2(float(x), float(y));
85 }
86 }
87
88 imageStore(texture0, texelCoord, currentValue);
89// memoryBarrier();
90}
91
92
93)""
94