framework2

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/*
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 *  GodRaysPass.cpp
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 *
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 *  Copyright (c) 2013, satcy, http://satcy.net
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 *  All rights reserved. 
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 *  
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 *  Redistribution and use in source and binary forms, with or without 
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 *  modification, are permitted provided that the following conditions are met: 
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 *  
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 *  * Redistributions of source code must retain the above copyright notice, 
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 *    this list of conditions and the following disclaimer. 
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 *  * Redistributions in binary form must reproduce the above copyright 
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 *    notice, this list of conditions and the following disclaimer in the 
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 *    documentation and/or other materials provided with the distribution. 
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 *  * Neither the name of Neil Mendoza nor the names of its contributors may be used 
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 *    to endorse or promote products derived from this software without 
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 *    specific prior written permission. 
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 *  
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 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
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 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
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 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
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 *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
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 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
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 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
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 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
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 *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
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 *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
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 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
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 *  POSSIBILITY OF SUCH DAMAGE. 
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 *
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 */
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#include "GodRaysPass.h"
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#include "ofMain.h"
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namespace itg
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{
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    GodRaysPass::GodRaysPass(const ofVec2f& aspect, bool arb, const ofVec3f & lightPositionOnScreen, float lightDirDOTviewDir) :
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        lightPositionOnScreen(lightPositionOnScreen), lightDirDOTviewDir(lightDirDOTviewDir), RenderPass(aspect, arb, "godrays")
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    {
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        string vertShaderSrc = STRINGIFY(
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            void main(void)
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            {
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                gl_TexCoord[0] = gl_MultiTexCoord0;
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                gl_FrontColor = gl_Color;
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                gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
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            }
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        );
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        string fragShaderSrc = STRINGIFY(
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            uniform sampler2D rtex;
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            uniform sampler2D otex;
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            const int NUM_SAMPLES = 50;
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            uniform vec2 lightPositionOnScreen;
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            uniform float lightDirDOTviewDir;
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            void main(void)
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            {
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                vec4 origColor = texture2D(otex, gl_TexCoord[0].st);
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                vec4 raysColor = texture2D(rtex, gl_TexCoord[0].st);
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                if (lightDirDOTviewDir>0.0){
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                    float exposure	= 0.1/float(NUM_SAMPLES);
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                    float decay		= 1.0 ;
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                    float density	= 0.5;
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                    float weight	= 6.0;
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                    float illuminationDecay = 1.0;
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                    vec2 deltaTextCoord = vec2( gl_TexCoord[0].st - lightPositionOnScreen);
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                    vec2 textCoo = gl_TexCoord[0].st;
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                    deltaTextCoord *= 1.0 / float(NUM_SAMPLES) * density;
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                    for(int i=0; i < NUM_SAMPLES ; i++)
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                    {
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                        textCoo -= deltaTextCoord;
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                        vec4 tsample = texture2D(rtex, textCoo );
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                        tsample *= illuminationDecay * weight;
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                        raysColor += tsample;
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                        illuminationDecay *= decay;
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                    }
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                    raysColor *= exposure * lightDirDOTviewDir;
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                    float p = 0.3 *raysColor.g + 0.59*raysColor.r + 0.11*raysColor.b;
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                    gl_FragColor = origColor + p;
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                } else {
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                    gl_FragColor = origColor;
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                }
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            }
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        );
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        shader.setupShaderFromSource(GL_VERTEX_SHADER, vertShaderSrc);
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        shader.setupShaderFromSource(GL_FRAGMENT_SHADER, fragShaderSrc);
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        shader.linkProgram();
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    }
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    void GodRaysPass::render(ofFbo& readFbo, ofFbo& writeFbo, ofTexture& depthTex)
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    {
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        writeFbo.begin();
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        shader.begin();
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        shader.setUniformTexture("otex", readFbo.getTexture(), 0);
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        shader.setUniformTexture("rtex", readFbo.getTexture(), 1);
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        shader.setUniform2f("lightPositionOnScreen", lightPositionOnScreen.x, lightPositionOnScreen.y);
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        shader.setUniform1f("lightDirDOTviewDir", lightDirDOTviewDir);
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        texturedQuad(0, 0, writeFbo.getWidth(), writeFbo.getHeight());
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        shader.end();
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        writeFbo.end();
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    }
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}