package com.test24;

import java.nio.FloatBuffer;

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

public class Camera {
	private float DEG2RAD = 3.141592653589793f / 180.0f;
	private Vector3f pos;
	private Vector3f left, up, forward;
	private float[] rotationMat;
	private FloatBuffer rotation;
	
	public Camera() {
		pos = new Vector3f(0.0f, 0.0f, 0.0f);
		left = new Vector3f(1.0f, 0.0f, 0.0f);
		up = new Vector3f(0.0f, 1.0f, 0.0f);
		forward = new Vector3f(0.0f, 0.0f, 1.0f);
		rotationMat = new float[16];
		rotation = BufferUtils.createFloatBuffer(16);
	}
	
	public void moveForward(float amount) {
		pos.x += forward.x * amount;
		pos.y += forward.y * amount;
		pos.z += forward.z * amount;
	}
	
	public void rotateX(float delta) {
		delta *= DEG2RAD;
		Vector3f cross = new Vector3f();
		Vector3f.cross(up, forward, cross);
		calcRotationMat(delta, cross);
		Vector3f newVect1 = new Vector3f(rotationMat[0] * forward.x + rotationMat[4] * forward.y + rotationMat[8] * forward.z, 
				rotationMat[1] * forward.x + rotationMat[5] * forward.y + rotationMat[9] * forward.z, 
				rotationMat[2] * forward.x + rotationMat[6] * forward.y + rotationMat[10] * forward.z);
		forward = newVect1;
		
		Vector3f newVect2 = new Vector3f(rotationMat[0] * up.x + rotationMat[4] * up.y + rotationMat[8] * up.z, 
				rotationMat[1] * up.x + rotationMat[5] * up.y + rotationMat[9] * up.z, 
				rotationMat[2] * up.x + rotationMat[6] * up.y + rotationMat[10] * up.z);
		up = newVect2;
	}
	
	public void rotateY(float delta) {
		delta *= DEG2RAD;
		calcRotationMat(delta, up);
		Vector3f newVect = new Vector3f(rotationMat[0] * forward.x + rotationMat[4] * forward.y + rotationMat[8] * forward.z, 
				rotationMat[1] * forward.x + rotationMat[5] * forward.y + rotationMat[9] * forward.z, 
				rotationMat[2] * forward.x + rotationMat[6] * forward.y + rotationMat[10] * forward.z);
		forward = newVect;
	}
	
	public void rotateZ(float delta) {
		delta *= DEG2RAD;
		calcRotationMat(delta, forward);
		Vector3f newVect = new Vector3f(rotationMat[0] * up.x + rotationMat[4] * up.y + rotationMat[8] * up.z, 
				rotationMat[1] * up.x + rotationMat[5] * up.y + rotationMat[9] * up.z, 
				rotationMat[2] * up.x + rotationMat[6] * up.y + rotationMat[10] * up.z);
		up = newVect;
	}
	
	public void calcRotationMat(float angle, Vector3f v) {
		float x = v.x;
		float y = v.y;
		float z = v.z;
		float mag = (float) (1.0f / Math.sqrt(x * x + y * y + z * z));
		x *= mag;
		y *= mag;
		z *= mag;
		float c = (float) Math.cos(angle);
		float s = (float) Math.sin(angle);
		
		float xx = x * x;
		float yy = y * y;
		float zz = z * z;
		float xy = x * y;
		float yz = y * z;
		float zx = z * x;
		float xs = x * s;
		float ys = y * s;
		float zs = z * s;
		float one_c = 1.0f - c;
		
		rotationMat[0] = (one_c * xx) + c;
		rotationMat[4] = (one_c * xy) - zs;
		rotationMat[8] = (one_c * zx) + ys;
		rotationMat[12] = 0.0f;
		
		rotationMat[1] = (one_c * xy) + zs;
		rotationMat[5] = (one_c * yy) + c;
		rotationMat[9] = (one_c * yz) - xs;
		rotationMat[13] = 0.0f;
		
		rotationMat[2] = (one_c * zx) - ys;
		rotationMat[6] = (one_c * yz) + xs;
		rotationMat[10] = (one_c * zz) + c;
		rotationMat[14] = 0.0f;
		
		rotationMat[3] = 0.0f;
		rotationMat[7] = 0.0f;
		rotationMat[11] = 0.0f;
		rotationMat[15] = 1.0f;
	}
	
	public void applyCameraTransform() {
		Vector3f z = forward.negate(null);
		left = Vector3f.cross(up, z, null);
		rotation.clear();
		float[] orient = new float[] {
				left.x, up.x, z.x, 0.0f, 
				left.y, up.y, z.y, 0.0f, 
				left.z, up.z, z.z, 0.0f, 
				0.0f, 0.0f, 0.0f, 1.0f
		};
		rotation.put(orient).flip();
		GL11.glMultMatrix(rotation);
		GL11.glTranslatef(-pos.x, -pos.y, -pos.z);
	}
}