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/*
** Copyright (c) 2012 The Khronos Group Inc.
**
** Permission is hereby granted, free of charge, to any person obtaining a
** copy of this software and/or associated documentation files (the
** "Materials"), to deal in the Materials without restriction, including
** without limitation the rights to use, copy, modify, merge, publish,
** distribute, sublicense, and/or sell copies of the Materials, and to
** permit persons to whom the Materials are furnished to do so, subject to
** the following conditions:
**
** The above copyright notice and this permission notice shall be included
** in all copies or substantial portions of the Materials.
**
** THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
** MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
*/
#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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