KaleidoscopePass.cpp

/*
 *  KaleidoscopePass.cpp
 *
 *  Copyright (c) 2012, Neil Mendoza, http://www.neilmendoza.com
 *  All rights reserved. 
 *  
 *  Redistribution and use in source and binary forms, with or without 
 *  modification, are permitted provided that the following conditions are met: 
 *  
 *  * Redistributions of source code must retain the above copyright notice, 
 *    this list of conditions and the following disclaimer. 
 *  * Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *  * Neither the name of Neil Mendoza nor the names of its contributors may be used 
 *    to endorse or promote products derived from this software without 
 *    specific prior written permission. 
 *  
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 *  POSSIBILITY OF SUCH DAMAGE. 
 *
 */
#include "KaleidoscopePass.h"

namespace itg
{
    KaleidoscopePass::KaleidoscopePass(const ofVec2f& aspect, bool arb, float segments) :
        segments(segments), RenderPass(aspect, arb, "kaleido")
    {
        string fragShaderSrc = STRINGIFY(
            uniform sampler2D tex;
            uniform float segments;
             
            void main()
            {
                vec2 uv = gl_TexCoord[0].st;
                vec2 normed = 2.0 * uv - 1.0;
                float r = length(normed);
                float theta = atan(normed.y / abs(normed.x));
                theta *= segments;
                
                vec2 newUv = (vec2(r * cos(theta), r * sin(theta)) + 1.0) / 2.0;
                 
                gl_FragColor = texture2D(tex, newUv);
            }
        );
        
        shader.setupShaderFromSource(GL_FRAGMENT_SHADER, fragShaderSrc);
        shader.linkProgram();
#ifdef _ITG_TWEAKABLE
        addParameter("segs", this->segments, "min=-20 max=20");
#endif
    }
    
    void KaleidoscopePass::render(ofFbo& readFbo, ofFbo& writeFbo, ofTexture& depth)
    {
        writeFbo.begin();
        
        shader.begin();
        
        shader.setUniformTexture("tex", readFbo.getTexture(), 0);
        shader.setUniform1f("segments", segments);
        
        texturedQuad(0, 0, writeFbo.getWidth(), writeFbo.getHeight());
        
        shader.end();
        writeFbo.end();
    }
}