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//
// Fragment shader for drawing Julia sets
//
// Authors: Dave Baldwin, Steve Koren, Randi Rost
// based on a shader by Michael Rivero
//
// Copyright (c) 2002-2004: 3Dlabs, Inc.
//
// See 3Dlabs-License.txt for license information
//
varying vec3 Position;
varying float LightIntensity;
uniform float MaxIterations;
uniform float Zoom;
uniform float Xcenter;
uniform float Ycenter;
uniform vec3 InnerColor;
uniform vec3 OuterColor1;
uniform vec3 OuterColor2;
uniform float Creal;
uniform float Cimag;
void main(void)
{
float real = Position.x * Zoom + Xcenter;
float imag = Position.y * Zoom + Ycenter;
//float Creal = real; // Change this line...
//float Cimag = imag; // ...and this one to get a Julia set
float r2 = 0.0;
float iter;
for (iter = 0.0; iter < MaxIterations && r2 < 4.0; ++iter)
{
float tempreal = real;
real = (tempreal * tempreal) - (imag * imag) + Creal;
imag = 2.0 * tempreal * imag + Cimag;
r2 = (real * real) + (imag * imag);
}
// Base the color on the number of iterations
vec3 color;
if (r2 < 4.0)
color = InnerColor;
else
color = mix(OuterColor1, OuterColor2, fract(iter * 0.05));
color *= LightIntensity;
gl_FragColor = vec4 (color, 1.0);
}
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