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);
        }
    }
}