package com.paul.persp;

import com.paul.persp.geom.Point4f;
import com.paul.persp.gfx.Screen;
import com.paul.persp.maths.Matrix4f;

public class Camera3D {
	private Matrix4f projMat;
	private Matrix4f viewMat;
	
	public Camera3D() {
		projMat = new Matrix4f();
		projMat.setIdentity();
		viewMat = new Matrix4f();
		viewMat.setIdentity();
	}
	
	public void setPerspectiveView(float fov, float aspectRatio, float near, float far) {
		float coTan2 = (float) (1.0f / Math.tan(Math.toRadians(fov * 0.5f)));
		float yScale = coTan2;
		float xScale = yScale / aspectRatio;
		
		projMat.set(0, xScale);
		projMat.set(1, 0.0f);
		projMat.set(2, 0.0f);
		projMat.set(3, 0.0f);
		
		projMat.set(4, 0.0f);
		projMat.set(5, yScale);
		projMat.set(6, 0.0f);
		projMat.set(7, 0.0f);
		
		projMat.set(8, 0.0f);
		projMat.set(9, 0.0f);
		projMat.set(10, -far / (near - far));
		projMat.set(11, -1.0f);
		
		projMat.set(12, 0.0f);
		projMat.set(13, 0.0f);
		projMat.set(14, -near * far / (near - far));
		projMat.set(15, 0.0f);
	}
	
	public void renderVertices(Point4f[] vertices, Screen screen) {
		for(int i = 0; i < vertices.length; i++) {
			Point4f transPos = Point4f.multiply(Point4f.multiply(vertices[i], viewMat), projMat);
			if(transPos.getX() < -1 || transPos.getX() > 1 || transPos.getY() < -1 || transPos.getY() > 1) continue;
			int x = (int) (Main.WIDTH * 0.5 + transPos.getX() * Main.WIDTH * 0.5 / transPos.getZ());
			int y = (int) (Main.HEIGHT * 0.5 + transPos.getY() * Main.HEIGHT * 0.5 / transPos.getZ());
			screen.drawPoint(x, y, 0xffffffff);
		}
	}
}