Triangle-Ray Intersection

//RAY TRIANGLE INTERSECTION 

// BY JOSE SANCHEZ

// REF: http://www.cs.princeton.edu/courses/archive/fall00/cs426/lectures/raycast/sld018.htm

// http://paulbourke.net/geometry/planeline/

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import toxi.geom.*;

import toxi.geom.mesh.*;

import peasy.*;

import toxi.processing.*;

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PeasyCam cam;

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Ray jRay;

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//Vec3D a = new Vec3D (0,0,-100);

//Vec3D b = new Vec3D (0,100,80);

//Vec3D c = new Vec3D (0,-100,40);

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Vec3D base = new Vec3D(300,0,50);

Vec3D rayDir = new Vec3D(-1,0,-0.1);

float rayLength = 2000;

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TriangleMesh mesh;

ToxiclibsSupport gfx;

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void setup() {

  size(800,600,P3D);

  cam = new PeasyCam(this, 100);

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  gfx = new ToxiclibsSupport(this);

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  //CALL INTERSECTION CLASS

  jRay = new Ray(base, rayDir, rayLength);

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  mesh = new TriangleMesh();

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  //BUILD A CILINDER:

  buildMesh( 30, 10, 40, 400);

}

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void draw() {

  background(0);

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  noFill();

  stroke(255);

  strokeWeight(1);

  //box(300);

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  fill(100,50);

  //rect(-150,-150,300,300);

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  gfx.mesh(mesh,false);

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  jRay.run();  

  jRay.intersectMesh(mesh);

  //jRay.intersectFace(a,b,c);

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  if(keyPressed) {

    saveFrame("im-####.png");

  }

}

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void buildMesh(int cols, int rows, float zScale, float rad) {

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  for(int i = 0; i < cols; i ++) {

    for(int j = 0; j < rows; j++) {

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      float angle1 = radians(360/(float(cols)) * i);

      float angle2 = radians(360/(float(cols)) * (i+1));

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      Vec3D a = new Vec3D(cos(angle1) * rad, sin(angle1)* rad, j*zScale);

      Vec3D b = new Vec3D(cos(angle2) * rad, sin(angle2)* rad, j*zScale);

      Vec3D c = new Vec3D(cos(angle2) * rad, sin(angle2)* rad, (j+1)*zScale);

      Vec3D d = new Vec3D(cos(angle1) * rad, sin(angle1)* rad, (j+1)*zScale);

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      mesh.addFace(a,b,c);

      mesh.addFace(c,d,a);

    }

  }

}

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