Function transformVertices

assets/js/block_ninja.js:466–496

(vertices, target, tX, tY, tZ, rX, rY, rZ, sX, sY, sZ)

// If `vertices` and `target` are different arrays, `vertices` will not be touched, instead the
// transformed values from `vertices` will be written to `target` array.
function transformVertices(vertices, target, tX, tY, tZ, rX, rY, rZ, sX, sY, sZ) {
	// Matrix multiplcation constants only need calculated once for all vertices.
	const sinX = Math.sin(rX);
	const cosX = Math.cos(rX);
	const sinY = Math.sin(rY);
	const cosY = Math.cos(rY);
	const sinZ = Math.sin(rZ);
	const cosZ = Math.cos(rZ);

	// Using forEach() like map(), but with a (recycled) target array.
	vertices.forEach((v, i) => {
		const targetVertex = target[i];
		// X axis rotation
		const x1 = v.x;
		const y1 = v.z*sinX + v.y*cosX;
		const z1 = v.z*cosX - v.y*sinX;
		// Y axis rotation
		const x2 = x1*cosY - z1*sinY;
		const y2 = y1;
		const z2 = x1*sinY + z1*cosY;
		// Z axis rotation
		const x3 = x2*cosZ - y2*sinZ;
		const y3 = x2*sinZ + y2*cosZ;
		const z3 = z2;

		// Scale, Translate, and set the transform.
		targetVertex.x = x3 * sX + tX;
		targetVertex.y = y3 * sY + tY;
		targetVertex.z = z3 * sZ + tZ;
	});
}

// 3D projection on a single vertex.
// Directly mutates the vertex.