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// Triangle
class Triangle {
// position
PVector p1, p2, p3;
// color
color c1, c2, c3;
BoundingBox bbx;
Triangle(PVector p1, PVector p2, PVector p3, color c1, color c2, color c3) {
this.p1 = p1;
this.p2 = p2;
this.p3 = p3;
this.c1 = c1;
this.c2 = c2;
this.c3 = c3;
bbx = new BoundingBox();
bbx.create(this);
}
// check to see if a ray intersects with the triangle
boolean intersect(Ray r, float[] param) {
PVector p21 = PVector.sub(p2, p1);
PVector p31 = PVector.sub(p3, p1);
PVector po1 = PVector.sub(r.ori, p1);
PVector dxp31 = r.dir.cross(p31);
PVector po1xp21 = po1.cross(p21);
float denom = p21.dot(dxp31);
float t = p31.dot(po1xp21) / denom;
float alpha = po1.dot(dxp31) / denom;
float beta = r.dir.dot(po1xp21) / denom;
boolean res = t > 0 && alpha > 0 && alpha < 1 && beta > 0 && beta < 1 &&
alpha + beta < 1;
// depth test
if (res && t < param[0]) {
param[0] = t;
param[1] = alpha * p1.x + beta * p2.x + (1 - alpha - beta) * p3.x;
param[2] = alpha * p1.y + beta * p2.y + (1 - alpha - beta) * p3.y;
param[3] = alpha * p1.z + beta * p2.z + (1 - alpha - beta) * p3.z;
}
return res;
}
void render() {
beginShape(TRIANGLES);
fill(c1);
vertex(p1.x, p1.y, p1.z);
fill(c2);
vertex(p2.x, p2.y, p2.z);
fill(c3);
vertex(p3.x, p3.y, p3.z);
endShape();
}
}
// Ray
class Ray {
// origin and direction
PVector ori, dir;
Ray(PVector ori, PVector dir) {
this.ori = ori;
this.dir = dir;
}
}
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