modern geometryShaderExample

main.cpp

#include "ofMain.h"

#define STRINGIFY(x) #x

class ofApp : public ofBaseApp
{
    
public:
    
    ofShader shader;
    ofEasyCam camera;
    ofVboMesh mesh;
    ofPlanePrimitive plane;
    ofSpherePrimitive sphere;
    void setup()
    {
        
        ofBackground(ofColor::black);
        ofSetVerticalSync(false);
        
        string shaderHeader = "#version 330\n";
        string vertShaderSource = shaderHeader;
        string fragShaderSource = shaderHeader;
        string geomShaderSource = shaderHeader;
        
        vertShaderSource += STRINGIFY(
                                      
                                      uniform mat4 modelViewProjectionMatrix;
                                      
                                      in vec4  position;
                                      in vec2  texcoord;
                                      
                                      out vec2 texCoordVarying;
                                      
                                      void main()
                                      {
                                          gl_Position = position;
                                      }
                                      );
        fragShaderSource += STRINGIFY(
                                      
                                      out vec4 fragColor;
                                      in vec4 outputColor;
                                      
                                      void main (void)
                                      {
                                          fragColor = outputColor;
                                      }
                                      );
        
        geomShaderSource += STRINGIFY(
                                      
                                      layout (points) in;
                                      layout (line_strip, max_vertices = 16) out;
                                      
                                      uniform mat4 modelViewProjectionMatrix;
                                      uniform vec4 globalColor;
                                      out vec4 outputColor;
                                      
                                      void main() {
                                          
                                          vec4 position = gl_in[0].gl_Position;
                                          float size = 10.f;
                                          vec4 NEU = position + vec4( size,  size,  size, 0.0);
                                          vec4 NED = position + vec4( size, -size,  size, 0.0);
                                          vec4 NWU = position + vec4( size,  size, -size, 0.0);
                                          vec4 NWD = position + vec4( size, -size, -size, 0.0);
                                          vec4 SEU = position + vec4(-size,  size,  size, 0.0);
                                          vec4 SED = position + vec4(-size, -size,  size, 0.0);
                                          vec4 SWU = position + vec4(-size,  size, -size, 0.0);
                                          vec4 SWD = position + vec4(-size, -size, -size, 0.0);
                                          
                                          gl_Position =  modelViewProjectionMatrix * NED;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * NWD;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * SWD;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * SED;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * SEU;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * SWU;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * NWU;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * NEU;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * NED;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * SED;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * SEU;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * NEU;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * NWU;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * NWD;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * SWD;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          gl_Position =  modelViewProjectionMatrix * SWU;
                                          outputColor = globalColor; EmitVertex();
                                          
                                          EndPrimitive();
                                          
                                      }
                                      );
        
     
        
        shader.setupShaderFromSource(GL_VERTEX_SHADER, vertShaderSource);
        shader.setupShaderFromSource(GL_FRAGMENT_SHADER, fragShaderSource);
        shader.setupShaderFromSource(GL_GEOMETRY_SHADER, geomShaderSource);
        shader.linkProgram();
        
        ofLog() << "Maximum number of output vertices support is: " << shader.getGeometryMaxOutputCount();
        
        plane.set(1000, 1000, 30, 30);
        sphere.set(100, 10);
        mesh = ofVboMesh(sphere.getMesh());
        mesh.setMode(OF_PRIMITIVE_POINTS);

    }
    
    void update()
    {
    }
    
    void draw()
    {
        camera.begin();
        shader.begin();
        mesh.draw();
        shader.end();
        //mesh.drawWireframe();
        camera.end();
        ofDrawBitmapString("FPS: " + ofToString(ofGetFrameRate(), 2), 20, 20);
    }
    
    void keyPressed (int key)
    {
        
    }
    
};


int main( ){
    ofSetLogLevel(OF_LOG_VERBOSE);
    ofGLFWWindowSettings settings;
    settings.setGLVersion(4, 1);
    settings.width = 1280;
    settings.height = 720;
    ofCreateWindow(settings);
    ofRunApp(new ofApp());
}