raytracing1.ts

import Playground from "./playground";
import { vecDotProduct, vecMultiplyScalar, vecSubtract } from "./utils";

const pg = new Playground();

const sphere = {
    position: [0, .5, -4], //C - Center of sphere
    radius: 2
}
pg.visCamera(-1);
pg.gridXZ()

const o = [0, 0, 0]; //O - Origin
const co = vecSubtract(o, sphere.position) // O - C
const rsq = sphere.radius * sphere.radius;

const step = 1/8

for (let yCoord = -1; yCoord <= 1; yCoord +=  step) {

    for (let xCoord = -1; xCoord <= 1; xCoord +=  step) {

        const v = [xCoord, yCoord, -1]
        const ov = vecSubtract(v, o); // V - O

        pg.visVector(ov)

        const a = vecDotProduct(ov, ov); // a = (V - O)*(V _ O)
        const b = 2* vecDotProduct(ov, co); // b = 2 * ((V - O)*(O - C))
        const c = vecDotProduct(co, co) - rsq; // c = ((O - C)*(O - C))-r^2
 
        const discriminant = (b*b) - (4*a*c); // b^2 - 4*a*c

        const t1 = (-b + Math.sqrt(discriminant)) / (2 * a)
        const t2 = (-b - Math.sqrt(discriminant)) / (2 * a)
        
        if (t1) {
            pg.visPoint(vecMultiplyScalar(v, t1),{color:"red"});
        }

        if (t2) {
            pg.visPoint(vecMultiplyScalar(v, t2),{color:"blue"});
        }

    }
}