59 lines
1.3 KiB
GLSL
59 lines
1.3 KiB
GLSL
#version 330
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// This source code is property of the Computer Graphics and Visualization
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// chair of the TU Dresden. Do not distribute!
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// Copyright (C) CGV TU Dresden - All Rights Reserved
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in vec4 position;
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uniform mat4 mvp;
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//Returns the height of the procedural terrain at a given xz position
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float getTerrainHeight(vec2 p);
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void main()
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{
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gl_Position = mvp * position;
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}
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//source: https://gist.github.com/patriciogonzalezvivo/670c22f3966e662d2f83
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float rand(vec2 c)
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{
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return 2 * fract(sin(dot(c.xy ,vec2(12.9898,78.233))) * 43758.5453) - 1;
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}
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float perlinNoise(vec2 p )
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{
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vec2 ij = floor(p);
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vec2 xy = p - ij;
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//xy = 3.*xy*xy-2.*xy*xy*xy;
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xy = .5*(1.-cos(3.1415926 * xy));
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float a = rand((ij+vec2(0.,0.)));
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float b = rand((ij+vec2(1.,0.)));
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float c = rand((ij+vec2(0.,1.)));
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float d = rand((ij+vec2(1.,1.)));
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float x1 = mix(a, b, xy.x);
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float x2 = mix(c, d, xy.x);
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return mix(x1, x2, xy.y);
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}
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//based on https://www.seedofandromeda.com/blogs/58-procedural-heightmap-terrain-generation
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float getTerrainHeight(vec2 p)
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{
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float total = 0.0;
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float maxAmplitude = 0.0;
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float amplitude = 1.0;
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float frequency = 0.02;
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for (int i = 0; i < 11; i++)
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{
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total += ((1.0 - abs(perlinNoise(p * frequency))) * 2.0 - 1.0) * amplitude;
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frequency *= 2.0;
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maxAmplitude += amplitude;
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amplitude *= 0.45;
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}
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return 15 * total / maxAmplitude;
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}
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