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/*
Copyright (c) 2019 The Khronos Group Inc.
Use of this source code is governed by an MIT-style license that can be
found in the LICENSE.txt file.
*/
#ifdef GL_ES
precision mediump float;
#endif
uniform float GrainSize;
uniform vec3 DarkColor;
uniform vec3 colorSpread;
varying float lightIntensity;
varying vec3 Position;
void main (void)
{
//
// cheap noise
//
vec3 location = Position;
vec3 floorvec = vec3(floor(Position.x * 10.0), 0.0, floor(Position.z * 10.0));
vec3 noise = Position * 10.0 - floorvec - 0.5;
noise *= noise;
location += noise * 0.12;
//
// distance from axis
//
float dist = location.x * location.x + location.z * location.z;
float grain = dist / GrainSize;
//
// grain effects as function of distance
//
float brightness = fract(grain);
if (brightness > 0.5)
brightness = (1.0 - brightness);
vec3 color = DarkColor + 0.5 * brightness * (colorSpread);
brightness = fract(grain*7.0);
if (brightness > 0.5)
brightness = 1.0 - brightness;
color -= 0.5 * brightness * colorSpread;
//
// also as a function of lines parallel to the axis
//
brightness = fract(grain*47.0);
float line = fract(Position.z + Position.x);
float snap = floor(line * 30.0) * (1.0/30.0);
if (line < snap + 0.004)
color -= 0.5 * brightness * colorSpread;
//
// apply lighting effects from vertex processor
//
color *= lightIntensity;
color = clamp(color, 0.0, 1.0);
gl_FragColor = vec4(color, 0.1)
}
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