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//
// Fragment shader for antialiased procedural bricks
//
// Authors: Dave Baldwin, Randi Rost
// based on a shader by Darwyn Peachey
//
// Copyright (c) 2002-2004 3Dlabs Inc. Ltd.
//
// See 3Dlabs-License.txt for license information
//
uniform vec3 BrickColor, MortarColor;
uniform vec2 BrickSize;
uniform vec2 BrickPct;
uniform vec2 MortarPct;
varying vec2 MCposition;
varying float LightIntensity;
#define Integral(x, p, notp) ((floor(x)*(p)) + max(fract(x)-(notp), 0.0))
void main(void)
{
vec2 position, fw, useBrick;
vec3 color;
// Determine position within the brick pattern
position = MCposition / BrickSize;
// Adjust every other row by an offset of half a brick
if (fract(position.y * 0.5) > 0.5)
position.x += 0.5;
// Calculate filter size
fw = fwidth(position);
// Perform filtering by integrating the 2D pulse made by the
// brick pattern over the filter width and height
useBrick = (Integral(position + fw, BrickPct, MortarPct) -
Integral(position, BrickPct, MortarPct)) / fw;
// Determine final color
color = mix(MortarColor, BrickColor, useBrick.x * useBrick.y);
color *= LightIntensity;
gl_FragColor = vec4 (color, 1.0);
}
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