Hey Everyone!
My end goal is to get the shader outlined here:
Example from Cinder forum link
Working in OF. With the aim of solving the Fat lines isssue which seems to come up here from time to time. I had had some luck with @roymacdonald 's ofxFatLines, however I wish to be able to change the fatness on many thousands of points frame to frame (Text outlines) and some quick experiments with that addon seemed that it may not be ideal for this purpose.
With that in mind then I started looking at the Geometry shader example supplied with OF (of_v0.11.2_vs2017_release\examples\gl\geometryShaderExample) which compiles and runs just fine.
I cannot however seem to successfully make any bold changes to the shader without receiving no output. Here is my edited shader (note the .frag and .vert shader remain unchanged from the example code):
#version 120
#extension GL_EXT_geometry_shader4 : enable
uniform float thickness; //not currently used
uniform vec3 color;
void main()
{
vec3 pos = gl_PositionIn[0].xyz;
gl_Position = gl_ModelViewProjectionMatrix * vec4(pos + vec3(-0.2, -0.2, 0.0), 0.0);
gl_FrontColor = vec4(color, 1.0f); //color is simply set to input
EmitVertex();
gl_Position = gl_ModelViewProjectionMatrix * vec4(pos + vec3( 0.2, -0.2, 0.0), 0.0);
gl_FrontColor = vec4(color, 1.0f);
EmitVertex();
gl_Position = gl_ModelViewProjectionMatrix * vec4(pos + vec3(-0.2, 0.2, 0.0), 0.0);
gl_FrontColor = vec4(color, 1.0f);
EmitVertex();
gl_Position = gl_ModelViewProjectionMatrix * vec4(pos + vec3( 0.2, -0.2, 0.0), 0.0);
gl_FrontColor = vec4(color, 1.0f);
EmitVertex();
//top
gl_Position = gl_ModelViewProjectionMatrix * vec4(pos + vec3( 0.0, 0.4, 0.0), 0.0);
gl_FrontColor = vec4(1.0f, 1.0f, 1.0f, 1.0f); // make the peak of the house white, just for fun.
EmitVertex();
//EndPrimitive(); // no effect
}
And here is Setup & Draw
void ofApp::setup(){
ofSetLogLevel(OF_LOG_VERBOSE);
ofBackground(50, 50, 50);
ofSetVerticalSync(false);
ofEnableAlphaBlending();
//shader.setGeometryInputType(GL_POINT); //no
//shader.setGeometryInputType(GL_POINTS); //no
shader.setGeometryInputType(GL_LINES); //still no
shader.setGeometryOutputType(GL_TRIANGLE_STRIP);
shader.setGeometryOutputCount(5);
shader.load("shaders/vert.glsl", "shaders/frag.glsl", "shaders/geom.glsl");
ofLog() << "Maximum number of output vertices support is: " << shader.getGeometryMaxOutputCount();
//vector of glm::vec3 to make Triangle;
points.push_back(glm::vec3(0.0f , 200.0f, 0.0f));
points.push_back(glm::vec3(200.0f, -200.0f, 0.0f));
points.push_back(glm::vec3(-200.0f, -200.0f, 0.0f));
points.push_back(glm::vec3(0.0f, 200.0f, 0.0f));
doShader = true;
ofEnableDepthTest();
}
void ofApp::draw(){
ofColor(255);
ofPushMatrix();
if(doShader) {
shader.begin();
shader.setUniform1f("thickness", 10); //not used
shader.setUniform3f("color", 1.0f, 0.69f, 0.0f);
}
ofTranslate(ofGetWidth() / 2, ofGetHeight() / 2, 0);
//Draw Tri
for(unsigned int i=1; i<points.size(); i++) {
ofDrawLine(points[i-1], points[i]);
}
if(doShader) shader.end();
ofPopMatrix();
ofDrawBitmapString("fps: " + ofToString((int)ofGetFrameRate()) + "\nPress 's' to toggle shader: " + (doShader ? "ON" : "OFF"), 20, 20);
}
What I’m expecting to see are three “house” shapes on each point descirbed by the incoming triangle as per this link:
Learn Open GL Geometry Shader Example
If anyone could steer me in the right direction, I would be very grateful!
