/**
* Tests this surface for intersection with ray. If an intersection is found record is filled out
* with the information about the intersection and the method returns true. It returns false
* otherwise and the information in outRecord is not modified.
*
* @param outRecord the output IntersectionRecord
* @param ray the ray to intersect
* @return true if the surface intersects the ray
*/
public boolean intersect(IntersectionRecord outRecord, Ray rayIn) {
// TODO#A2: fill in this function.
Vector3d p = rayIn.origin.clone().sub(center);
Vector3d d = rayIn.direction.clone();
double discr = Math.pow(d.dot(p), 2) - (d.dot(d)) * (p.dot(p) - Math.pow(radius, 2));
if (discr >= 0) {
double tPlus = (-d.dot(p) + Math.sqrt(discr)) / d.dot(d);
double tMinus = (-d.dot(p) - Math.sqrt(discr)) / d.dot(d);
double t = Math.min(tPlus, tMinus);
if (t > rayIn.end || t < rayIn.start) return false;
Vector3d intersect = new Vector3d();
rayIn.evaluate(intersect, t);
outRecord.location.set(intersect);
Vector3d normal = intersect.clone().sub(center).normalize();
outRecord.normal.set(normal);
outRecord.t = t;
outRecord.surface = this;
return true;
}
return false;
}
@Override
public void getColor(float u, float v, Color outColor) {
// TODO A4
// get our position if sphere is at 0, radius 1 (all that matters is ratios)
Vector3d pt = getPositionFromUV(u, v);
// create TBN inverse matrix
Vector3d normal = (new Vector3d(pt.x, pt.y, pt.z)).normalize();
Vector3d tangent;
if (u < .25 || (u > .5 && u < .75)) {
tangent = (new Vector3d(1 / pt.x, 0, -1 / pt.z)).normalize();
} else {
tangent = (new Vector3d(-1 / pt.x, 0, 1 / pt.z)).normalize();
}
Vector3d bitangent = (normal.clone().cross(tangent.clone())).normalize();
Matrix3d invTBN =
(new Matrix3d(
tangent.x,
bitangent.x,
normal.x,
tangent.y,
bitangent.y,
normal.y,
tangent.z,
bitangent.z,
normal.z))
.invert();
// ~-- The rest of this function calculates the new normal --~
Vector3d newNormal = new Vector3d();
// first determine distance to closest disk center
float divSize = (float) (1.0 / resolution);
// -calculate column
float modU = u % divSize;
float closestColumn = (u - modU) / divSize;
if (modU > divSize / 2) {
closestColumn++;
}
// -calculate row
float modV = v % divSize;
float closestRow = (v - modV) / divSize;
if (modV > divSize / 2) {
closestRow++;
}
// -calculate distance
float centerX = closestColumn * divSize;
float centerY = closestRow * divSize;
double distanceToCenter = Math.sqrt(Math.pow((centerX - u), 2) + Math.pow((centerY - v), 2));
// If we are on disk, use normal from disk center
// (the following formula ensures a bumpRadius of 0.5 is tangent circles, and >=1 is full
// overlap)
double diskRadius = (divSize / 2) * (Math.sqrt(2 * bumpRadius));
if (distanceToCenter <= diskRadius) {
Vector3d diskNormal = getPositionFromUV(centerX, centerY).normalize();
newNormal = multByMatrix(diskNormal, invTBN).normalize();
}
// if not on disk, use position normalized as normal
else {
newNormal = multByMatrix(normal, invTBN).normalize();
}
// Convert from [-1,1] to [0,1] to [0, 255]
Vector3d converted = new Vector3d();
converted.setMultiple(0.5, newNormal.clone().normalize());
converted.add(0.5);
Colord outColorAccurate = new Colord(converted);
outColor.set(outColorAccurate);
}