openFrameworks tutorial, part II: Texture Mapping - mesh.addTexCoord(ofPoint()) args error

beginners
#1

Hi! I was going through this nice tutorial and ran into a snag when my code would not compile. it has to do with ofMesh and adding texture coordinates. I seem to be giving the correct args when calling mesh.addTexCoord(ofPoint()) but i get an error message. Does anyone have insight on what i’m doing wrong? thanks!!

this is the url of the tutorial :

http://clab.concordia.ca/openframeworks-tutorial-part-ii-texture-mapping/

the error is in this line :

mesh.addTexCoord(ofPoint(x * (videoWidth / W), y * (videoHeight / H)));

error message is :

No viable conversion from ‘ofPoint’ (aka ‘ofVec3f’) to ‘const glm::vec<2, float, glm::packed_highp>’

this is the code for the implementation :

void ofApp::setup(){

// some code not included

//Set up vertices
for (int y=0; y<H; y++)
{
for (int x=0; x<W; x++)
{
// adding texture coordinates allows us to bind textures to it later
// --> this could be made into a function so that textures can be swapped / updated
mesh.addVertex(ofPoint((x - W/2) * meshSize, (y - H/2) * meshSize, 0));
mesh.addTexCoord(ofPoint(x * (videoWidth / W), y * (videoHeight / H)));
mesh.addColor(ofColor(255, 255, 255));
}
}

// some code not included

}

and here are the definitions in the .h file :

#pragma once

#include “ofMain.h”

class ofApp : public ofBaseApp{

public :

// some code not included

ofVideoPlayer video; //Prerecorded video

ofFbo fbo;

ofMesh mesh;

ofImage image;

ofPixels fboPixels;

private:

int videoHeight = 1080;

int videoWidth = 1920;

int W = 100; //Grid size

int H = 100;

int meshSize = 6;

float tiltCurrent = 0;

float tiltTarget = 0;

float turnCurrent = 1;

float turnTarget = 1;

};

#2

I think issue is ofPoint is 3 floats (an x, y & z coordinate) but texCoords are 2 dimensional.

if you change the ofPoint(…) to glm::vec2(…) it should compile ok

1 Like
#3

Thank you! I was able to compile with your changes.

#4

Yeah cool, just for reference, oF has changed from using its own vector types to using glm, which is more of an industry standard library.

Wherever you see ofVec2/3/4f or ofMat you can replace it with glm::vec2/3/4 or glm::mat if you have any issues.

I think all of the oF docs and examples have switched but theres still plenty of examples out there from other sources that might need a bit of updating. Just something to be aware of.

1 Like
#5

Great! Very helpful information!

I’m having an issue. When my video renders to the screen I can hear the video audio but no image. I just get a black screen which is the background. if I comment out the background, my rendering window is the default color. I’m using an fbo object. I think it has to do with the fbo object reading the video file maybe within this if statement:

if (video.isFrameNew())
{
// draw video into fbo
fbo.begin();

  int alpha = 20; // amount of smoothing
  ofEnableAlphaBlending();
  ofSetColor(255, 255, 255, alpha);

  // draw image into fbo
  video.draw(0, 0);
  ofDisableAlphaBlending();
  fbo.end();

}

here is the full code:

ofApp.h :

#pragma once

#include "ofMain.h"

class ofApp : public ofBaseApp{

	public:
		void setup();
		void update();
		void draw();

		void keyPressed(int key);
		void keyReleased(int key);
		void mouseMoved(int x, int y );
		void mouseDragged(int x, int y, int button);
		void mousePressed(int x, int y, int button);
		void mouseReleased(int x, int y, int button);
		void mouseEntered(int x, int y);
		void mouseExited(int x, int y);
		void windowResized(int w, int h);
		void dragEvent(ofDragInfo dragInfo);
		void gotMessage(ofMessage msg);
      ofVideoPlayer video; //Prerecorded video
      ofFbo fbo;
      ofMesh mesh;
      ofImage image;
      ofPixels fboPixels;
      
   private:
      int videoHeight = 1080;
      int videoWidth = 1920;
      int W = 100; //Grid size
      int H = 100;
      int meshSize = 6;
      float tiltCurrent = 0;
      float tiltTarget = 0;
      float turnCurrent = 1;
      float turnTarget = 1;

		
};

ofApp.cpp :

#include "ofApp.h"

//--------------------------------------------------------------
void ofApp::setup(){
   video.load( "IMG_1943.mov" ); //Load the video file
   video.play(); //Start the video

   //setup fbo
   fbo.allocate(videoWidth, videoHeight);
   // clear fbo
   fbo.begin();
   ofClear(255,255,255, 0);
   fbo.end();

   if (video.isFrameNew())
   {
      // draw video into fbo
      fbo.begin();

      int alpha = 20; // amount of smoothing
      ofEnableAlphaBlending();
      ofSetColor(255, 255, 255, alpha);

      // draw image into fbo
      video.draw(0, 0);
      ofDisableAlphaBlending();
      fbo.end();
   }

   //Set up vertices
   for (int y=0; y<H; y++)
   {
      for (int x=0; x<W; x++)
      {
            // adding texure coordinates allows us to bind textures to it later
            // --> this could be made into a function so that textures can be swapped / updated
            mesh.addVertex(ofPoint((x - W/2) * meshSize, (y - H/2) * meshSize, 0));
            mesh.addTexCoord(glm::vec2(x * (videoWidth / W), y * (videoHeight / H)));
            mesh.addColor(ofColor(255, 255, 255));
      }
   }

   //Set up triangles' indices
   for (int y=0; y<H-1; y++)
   {
      for (int x=0; x<W-1; x++)
      {
         int i1 = x + W * y;
         int i2 = x+1 + W * y;
         int i3 = x + W * (y+1);
         int i4 = x+1 + W * (y+1);
         mesh.addTriangle( i1, i2, i3 );
         mesh.addTriangle( i2, i4, i3 );
      }
   }

   //convert fbo to ofImage format
   fbo.readToPixels(fboPixels);
   image.setFromPixels(fboPixels);

}

//--------------------------------------------------------------
void ofApp::update(){
   video.update();

   //Change vertices
   for (int y=0; y<H; y++)
   {
      for (int x=0; x<W; x++)
      {

         //Vertex index
         int i = x + W * y;
         ofPoint p = mesh.getVertex( i );

         float scaleX = videoWidth / W;
         float scaleY = videoHeight / H;

         // get brightness
         int index = ((x * scaleX) + videoWidth * (y * scaleY)) * 4; // FBO has four components (including Alpha)
         int brightness = fboPixels[index] / 4; // 4 is an arbitrary scalar to reduce the amount of distortion

         //Change z-coordinate of vertex
         p.z = ofNoise(x * 0.05, y * 0.05, ofGetElapsedTimef() * 0.5) * 100;
         mesh.setVertex( i, p );

         //Change color of vertex
         mesh.setColor(i , ofColor(255, 255, 255));
      }
   }


}

//--------------------------------------------------------------
void ofApp::draw(){
   //Set background to black and rendering color to white
//   ofBackground(0);
   ofSetHexColor(0xffffff);
   fbo.draw(0, 0);

   ofPushMatrix(); //Store the coordinate system

   //Move the coordinate center to screen's center
   ofTranslate( ofGetWidth()/2, ofGetHeight()/2, 0 );

   tiltCurrent = ofLerp(tiltCurrent, tiltTarget, 0.1);
   turnCurrent = ofLerp(turnCurrent, turnTarget, 0.1);
   ofRotateX(tiltCurrent);
   ofRotateZ(turnCurrent);

   //Draw mesh
   image.bind();
   mesh.draw();
   image.unbind();
   // mesh.drawWireframe();

   ofPopMatrix(); //Restore the coordinate system

}

//--------------------------------------------------------------
void ofApp::keyPressed(int key){
   if (key == OF_KEY_DOWN)
   {
      tiltTarget -= 5;
   }
   else if (key == OF_KEY_UP)
   {
      tiltTarget += 5;
   }
   else if (key == OF_KEY_LEFT)
   {
      turnTarget -= 5;
   }
   else if (key == OF_KEY_RIGHT)
   {
      turnTarget += 5;
   }

}
#6

I think you need to move the if (video.isFrameNew()) { ... } to update, setup is only called at the start while update is called every frame.

second, i think you need to call image.update() after the .setFromPixels()

If you’re not doing any processing on the pixels themselves, you can skip the whole image thing and call fbo.getTextureReference().bind()/.unbind() when you draw the mesh