primitives.ts

import { vec3 } from 'gl-matrix';
import { cacheByContext } from './utils';

export const generateRectVerticesStrip = (
    x: number,
    y: number,
    width: number,
    height: number
) => [x, y, x, y + height, x + width, y, x + width, y + height];

export const rectVerticesStripUV = [0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 1.0, 1.0];
export const rectVerticesStripUVInverted = [
    0.0, 1.0, 0.0, 0.0, 1.0, 1.0, 1.0, 0.0,
];

export const rectVerticesStripNormal = [
    0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0,
];

export const generateRectVertices = (
    x: number,
    y: number,
    width: number,
    height: number
) => [
    x,
    y,
    x,
    y + height,
    x + width,
    y,
    x + width,
    y,
    x,
    y + height,
    x + width,
    y + height,
];

export const rectVerticesUV = [
    0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 1.0, 1.0,
];

const staticBufferGenerator =
    (data: number[]) => (gl: WebGL2RenderingContext) => {
        const buffer = gl.createBuffer();

        gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(data), gl.STATIC_DRAW);

        return buffer;
    };

export const getUnitRectPositionBuffer = cacheByContext(
    staticBufferGenerator(generateRectVerticesStrip(0, 0, 1, 1))
);
export const getUnitRectUVBuffer = cacheByContext(
    staticBufferGenerator(rectVerticesStripUV)
);
export const getUnitRectUVBufferInverted = cacheByContext(
    staticBufferGenerator(rectVerticesStripUVInverted)
);
export const getUnitRectNormalBuffer = cacheByContext(
    staticBufferGenerator(rectVerticesStripNormal)
);

export const CUBE_VERTICES = [
    1, 1, -1, 1, -1, -1, 1, 1, 1, 1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, 1, -1,
    -1, 1,
];

export const CUBE_INDICES = [
    4, 2, 0, 2, 7, 3, 6, 5, 7, 1, 7, 5, 0, 3, 1, 4, 1, 5, 4, 6, 2, 2, 6, 7, 6,
    4, 5, 1, 3, 7, 0, 2, 3, 4, 0, 1,
];

export const CUBE_LINE_INDICES = [
    0, 1, 0, 2, 1, 5, 2, 3, 2, 6, 3, 1, 4, 0, 4, 5, 5, 7, 6, 4, 7, 3, 7, 6,
];

export const generateCircleVertices = (vertexCount: number): number[] => {
    const origin = vec3.create();

    const firstVertex = vec3.create();
    vec3.set(firstVertex, 1, 0, 0);

    const vertices = [];
    const rotation = (2 * Math.PI) / vertexCount;

    const vertex = vec3.create();
    for (let i = 0; i < vertexCount; i++) {
        vec3.rotateY(vertex, firstVertex, origin, i * rotation);

        vertices.push(vertex[0]);
        vertices.push(vertex[1]);
        vertices.push(vertex[2]);
    }

    return vertices;
};