suzanne/lib/js/VaryingInterpolator/VaryingInterpolator3.js

3D Software Renderer

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const MathUtils_1 = require("../Utils/MathUtils");
const VaryingInterpolator_1 = require("./VaryingInterpolator");
class VaryingInterpolator3 extends VaryingInterpolator_1.VaryingInterpolator {
    constructor(a, b, c, VAO) {
        super(VAO, a, b, c);
        this._inv_dx = 1 /
            (((b.ndc.x - c.ndc.x) *
                (a.ndc.y - c.ndc.y)) -
                ((a.ndc.x - c.ndc.x) *
                    (b.ndc.y - c.ndc.y)));
        this._inv_dy = -this._inv_dx;
        this._computeGradients();
    }
    _computeGradients() {
        // http://web.cs.ucdavis.edu/~amenta/s12/perspectiveCorrect.pdf
        const one_over_z_a = this._vertices[0].ndc.w;
        const one_over_z_b = this._vertices[1].ndc.w;
        const one_over_z_c = this._vertices[2].ndc.w;
        for (const name of this._VAO.varyingNames) {
            const current_varyings = this._VAO.varyings.get(name);
            //apply perspective correct texture mapping:
            if (name !== '__ndc') {
                current_varyings[this._vertices[0].index] =
                    MathUtils_1.interpolableTimes(current_varyings[this._vertices[0].index], one_over_z_a);
                current_varyings[this._vertices[1].index] =
                    MathUtils_1.interpolableTimes(current_varyings[this._vertices[1].index], one_over_z_b);
                current_varyings[this._vertices[2].index] =
                    MathUtils_1.interpolableTimes(current_varyings[this._vertices[2].index], one_over_z_c);
            }
            let varying_a = current_varyings[this._vertices[0].index];
            let varying_b = current_varyings[this._vertices[1].index];
            let varying_c = current_varyings[this._vertices[2].index];
            if (typeof varying_a === 'number') {
                this._varyings.set(name, this._computeFloatGradient(varying_a, varying_b, varying_c));
            }
            else {
                this._varyings.set(name, this._computeVecGradient(varying_a, varying_b, varying_c));
            }
        }
    }
    _computeFloatGradient(a, b, c) {
        const ac_delta_y = this._vertices[0].ndc.y - this._vertices[2].ndc.y;
        const bc_delta_y = this._vertices[1].ndc.y - this._vertices[2].ndc.y;
        const x_step = (b - c) * (ac_delta_y) - ((a - c) * (bc_delta_y)) * (this._inv_dx);
        const ac_delta_x = this._vertices[0].ndc.x - this._vertices[2].ndc.x;
        const bc_delta_x = this._vertices[1].ndc.x - this._vertices[2].ndc.x;
        const y_step = (b - c) * (ac_delta_x) - ((a - c) * (bc_delta_x)) * (this._inv_dy);
        return { x_step, y_step };
    }
    _computeVecGradient(a, b, c) {
        const ac_delta_y = this._vertices[0].ndc.y - this._vertices[2].ndc.y;
        const bc_delta_y = this._vertices[1].ndc.y - this._vertices[2].ndc.y;
        const b_sub_c = b.sub(c);
        const a_sub_c = a.sub(c);
        const x_step = b_sub_c.times(ac_delta_y).sub(a_sub_c.times(bc_delta_y)).times(this._inv_dx);
        const ac_delta_x = this._vertices[0].ndc.x - this._vertices[2].ndc.x;
        const bc_delta_x = this._vertices[1].ndc.x - this._vertices[2].ndc.x;
        const y_step = b_sub_c.times(ac_delta_x).sub(a_sub_c.times(bc_delta_x)).times(this._inv_dy);
        return { x_step, y_step };
    }
}
exports.VaryingInterpolator3 = VaryingInterpolator3;