EdgePass.cpp

/*
 *  EdgePass.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 "EdgePass.h"

namespace itg
{
    EdgePass::EdgePass(const ofVec2f& aspect) : RenderPass(aspect, "edge")
    {
        string fragShaderSrc = STRINGIFY(
            uniform sampler2D tex;
            
            uniform vec2 aspect;
                                  
            vec2 texel = vec2(1.0 / aspect.x, 1.0 / aspect.y);

            // TODO: hard code matrix values!!!!
            mat3 G[9] = mat3[](1.0/(2.0*sqrt(2.0)) * mat3( 1.0, sqrt(2.0), 1.0, 0.0, 0.0, 0.0, -1.0, -sqrt(2.0), -1.0 ),
                                1.0/(2.0*sqrt(2.0)) * mat3( 1.0, 0.0, -1.0, sqrt(2.0), 0.0, -sqrt(2.0), 1.0, 0.0, -1.0 ),
                                1.0/(2.0*sqrt(2.0)) * mat3( 0.0, -1.0, sqrt(2.0), 1.0, 0.0, -1.0, -sqrt(2.0), 1.0, 0.0 ),
                                1.0/(2.0*sqrt(2.0)) * mat3( sqrt(2.0), -1.0, 0.0, -1.0, 0.0, 1.0, 0.0, 1.0, -sqrt(2.0) ),
                                1.0/2.0 * mat3( 0.0, 1.0, 0.0, -1.0, 0.0, -1.0, 0.0, 1.0, 0.0 ),
                                1.0/2.0 * mat3( -1.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0, 0.0, -1.0 ),
                                1.0/6.0 * mat3( 1.0, -2.0, 1.0, -2.0, 4.0, -2.0, 1.0, -2.0, 1.0 ),
                                1.0/6.0 * mat3( -2.0, 1.0, -2.0, 1.0, 4.0, 1.0, -2.0, 1.0, -2.0 ),
                                1.0/3.0 * mat3( 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 ));
                                  
            void main(void)
            {
                mat3 I;
                float cnv[9];
                vec3 sample;
            
                /* fetch the 3x3 neighbourhood and use the RGB vector's length as intensity value */
                for (int i=0; i<3; i++)
                {
                    for (int j=0; j<3; j++)
                    {
                        sample = texture2D(tex, gl_TexCoord[0].st + texel * vec2(i-1.0,j-1.0), 0 ).rgb;
                        I[i][j] = length(sample); 
                    }
                }

                /* calculate the convolution values for all the masks */
                for (int i=0; i<9; i++)
                {
                    float dp3 = dot(G[i][0], I[0]) + dot(G[i][1], I[1]) + dot(G[i][2], I[2]);
                    cnv[i] = dp3 * dp3; 
                }

                float M = (cnv[0] + cnv[1]) + (cnv[2] + cnv[3]);
                float S = (cnv[4] + cnv[5]) + (cnv[6] + cnv[7]) + (cnv[8] + M); 

                gl_FragColor = vec4(vec3(sqrt(M/S)), 1.0);
            }
        );
        
        shader.setupShaderFromSource(GL_FRAGMENT_SHADER, "#version 120\n" + fragShaderSrc);
        shader.linkProgram();
    }
    
    void EdgePass::render(ofFbo& readFbo, ofFbo& writeFbo)
    {
        writeFbo.begin();
        
        shader.begin();
        shader.setUniformTexture("tex", readFbo.getTextureReference(), 0);
        shader.setUniform2f("aspect", aspect.x, aspect.y);
        
        texturedQuad(0, 0, writeFbo.getWidth(), writeFbo.getHeight());
        
        shader.end();
        writeFbo.end();
    }
}