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41 lines
1.1 KiB
GLSL
41 lines
1.1 KiB
GLSL
#version 120
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// www.OpenTK.net GLSL Julia Set (c) 2008 Christoph Brandtner
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uniform sampler1D COLORTABLE;
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uniform float CETX;
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uniform float CETY;
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uniform float SCALINGX;
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uniform float SCALINGY;
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uniform float OFFSETX;
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uniform float OFFSETY;
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const int MAXIterations = 32; // *must* be > 0
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void main(void)
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{
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float XPos = gl_FragCoord.x / SCALINGX - OFFSETX;
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float YPos = gl_FragCoord.y / SCALINGY - OFFSETY;
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float XQuad = pow( XPos, 2.0 );
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float YQuad = pow( YPos, 2.0 );
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int TableIndex = -1;
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int LoopCount = 0;
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while ( LoopCount <= MAXIterations )
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{
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YPos = 2.0 * XPos * YPos + CETY;
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XPos = XQuad - YQuad + CETX;
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XQuad = pow( XPos, 2.0 );
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YQuad = pow( YPos, 2.0 );
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TableIndex++;
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if ( (XQuad + YQuad) > 4.0 )
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{
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if (TableIndex == 0)
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discard;
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LoopCount = MAXIterations;
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}
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LoopCount++;
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}
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float FinalTableIndex = float( TableIndex ) / float( MAXIterations );
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gl_FragColor = texture1D( COLORTABLE, FinalTableIndex ); // lookup texture for output
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// gl_FragColor.rgb = vec3( FinalTableIndex ); // Debug: output greyscale
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} |