Revised Raycasting utility

package com.windpoweredgames.mocha.util;

import java.util.Collection;

import org.lwjgl.opengl.GL11;
import org.lwjgl.util.vector.Vector3f;

import com.windpoweredgames.mocha.GameEngine;
import com.windpoweredgames.mocha.component.TextComponent;
import com.windpoweredgames.mocha.model.Model;
import com.windpoweredgames.mocha.model.matrix.ModelMatrix;

public class RayCastUtil {

    public static TextComponent rayStartComp = new TextComponent("RayStart");
    public static TextComponent rayDirComp = new TextComponent("RayDir");

    public static TextComponent dotComp = new TextComponent("DOT");
    public static TextComponent tComp = new TextComponent("T");
    public static TextComponent intersectionComp = new TextComponent("IntPoint");
    public static TextComponent hitComp = new TextComponent("HitPoint");
    public static TextComponent fullAreaComp = new TextComponent("Full Area");
    public static TextComponent area1Comp = new TextComponent("Area1");
    public static TextComponent area2Comp = new TextComponent("Area2");
    public static TextComponent area3Comp = new TextComponent("Area3");
    public static TextComponent areaTotalComp = new TextComponent("Total Area");
    public static Vector3f triag1 = new Vector3f();
    public static Vector3f triag2 = new Vector3f();
    public static Vector3f triag3 = new Vector3f();
    public static Vector3f normal = new Vector3f();
    public static final float ACCURACY = 0.00001f;




    public static Vector3f rayTest(Vector3f rayOrigin, Vector3f rayDirection, Model model){
        float[] vertexes = new float[model.getVertexBuffer().limit()];
        float[] normals =  new float[model.getNormalBuffer().limit()];
        model.getVertexBuffer().rewind();
        model.getVertexBuffer().get(vertexes);
        model.getNormalBuffer().rewind();
        model.getNormalBuffer().get(normals);
        Vector3f pos = model.getModelMatrix().getPosition();
        Vector3f result = null;
        float    resultDist = Float.MAX_VALUE;

        for(int i=0;i<vertexes.length;){
            // fix we need to adjust the triangle coords by the model position
            Vector3f normal = new Vector3f(normals[i+0],normals[i+1],normals[i+2]);
            Vector3f point1 = new Vector3f(vertexes[i]+pos.x,vertexes[i+1]+pos.y,vertexes[i+2]+pos.z);
            Vector3f point2 = new Vector3f(vertexes[i+3]+pos.x,vertexes[i+4]+pos.y,vertexes[i+5]+pos.z);
            Vector3f point3 = new Vector3f(vertexes[i+6]+pos.x,vertexes[i+7]+pos.y,vertexes[i+8]+pos.z);
            Vector3f tempResult =  rayTest(rayOrigin, rayDirection, normal,point1, point2, point3);
            if(tempResult!=null){
                float d = VectorUtil.distance(rayOrigin, tempResult);
                if(d < resultDist){
                    resultDist = d;
                    result = tempResult;
                }
            }
            i+=9;
        }
        return result;
    }




    public static  Vector3f rayTest(Vector3f rayOrigin, Vector3f rayDirection, Vector3f planeNormal, Vector3f trianglePoint1, Vector3f trianglePoint2, Vector3f trianglePoint3){
        rayStartComp.setText("RayStart = "+rayOrigin);
        rayDirComp.setText("RayDir = "+rayDirection);
        intersectionComp.setText("IntPoint");


        triag1 = trianglePoint1;
        triag2 = trianglePoint2;
        triag3 = trianglePoint3;
        normal = planeNormal;


        // nx, ny, nz : normal vector of the plane
        // x0, y0, z0 = a point on the plane

        // RAY properties...
        // x = xs+t*xd
        // y = ys+t*yd
        // z = zs+t*zd
        // xs, ys, zs = starting point of ray
        // xd, yd, zd = direction of ray

        // the raw equation we use.
        //t=(x0*nx+y0*ny+z0*nz-nx*nx-ny*ya-nz*zs) / (xd*nx+yd*ny+zd*nz)
        //                                        / <this part is the dot factor


        Vector3f pointOnPLane = trianglePoint1; // any point should work as long as its on the plane.
         //    a=    xd           *     nx      +         yd   *     ny      +      zd      *    nz;
        float dot = rayDirection.x*planeNormal.x+rayDirection.y*planeNormal.y+rayDirection.z*planeNormal.z;
        dotComp.setText("DOT = "+dot);
        float t=0;
        // if dot = 0 then the ray is pararel and will never intersect the plane. T should = 0 in this case.
        // if dot < 0 then the ray intersects but it does so in the opposite direction of the cast. so basically this should be treated as a miss.
        // leave t equal to 0
        if(dot == 0){
            return null; // this line is parrel and will never touch
        }
        //                   (p1.x       *    nx       +  p1.y        *      ny     +   p1.z       *    nz       -   nx        *  xs        -   ny           *     ys    -    nz       *   zs)
        float coordRatio = pointOnPLane.x*planeNormal.x+pointOnPLane.y*planeNormal.y+pointOnPLane.z*planeNormal.z-planeNormal.x*rayOrigin.x -   planeNormal.y*rayOrigin.y-planeNormal.z*rayOrigin.z;
        t = coordRatio / dot;
        tComp.setText("T = "+t);
        if(t<0){ // if t<0 then they intersect but the direction of intersection is opposite the cast direction.
            return null;
        }
        // t can be thought of like a distance factor down the ray. Using it we can resolve the exact points (x,y,z) where the ray hits the plane.
        // now lets figure out the intersect point

        float intX = rayOrigin.x+t*rayDirection.x;
        float intY = rayOrigin.y+t*rayDirection.y ;
        float intZ = rayOrigin.z+t*rayDirection.z;

        Vector3f intPoint = new Vector3f(intX,intY,intZ);
        intersectionComp.setText("IntPoint = "+intPoint);

        float fullArea = calculateTriangleArea(trianglePoint1, trianglePoint2, trianglePoint3);
        fullAreaComp.setText("Full Area = "+fullArea);

        float subTriangle1 = calculateTriangleArea(trianglePoint1, trianglePoint2, intPoint);
        area1Comp.setText("Area1 = "+subTriangle1);

        float subTriangle2 = calculateTriangleArea(trianglePoint2, trianglePoint3, intPoint);
        area2Comp.setText("Area2 = "+subTriangle2);

        float subTriangle3 = calculateTriangleArea(trianglePoint1, trianglePoint3, intPoint);
        area3Comp.setText("Area3 = "+subTriangle3);

        float totalSubAreas = subTriangle1 + subTriangle2 +subTriangle3;
        areaTotalComp.setText("Area Total = "+ totalSubAreas);

        // have an accuracy approach is import cause rounding errors will happen when doing Math.sqr. !
        if(Math.abs(fullArea- totalSubAreas)<ACCURACY){
            hitComp.setText("HIT");
            return intPoint;
        }else{
            hitComp.setText("MISS");
            return null;
        }

    }




    private static float calculateTriangleArea(Vector3f p1, Vector3f p2, Vector3f p3){
        float a = (float)Math.sqrt((p2.x-p1.x)*(p2.x-p1.x)+(p2.y-p1.y)*(p2.y-p1.y)+(p2.z-p1.z)*(p2.z-p1.z));
        float b = (float)Math.sqrt((p3.x-p2.x)*(p3.x-p2.x)+(p3.y-p2.y)*(p3.y-p2.y)+(p3.z-p2.z)*(p3.z-p2.z));
        float c = (float)Math.sqrt((p3.x-p1.x)*(p3.x-p1.x)+(p3.y-p1.y)*(p3.y-p1.y)+(p3.z-p1.z)*(p3.z-p1.z));
        float s = (a+b+c)/2;
        float result = (float)Math.sqrt(s*(s-a)*(s-b)*(s-c));
        return result;
    }




}