@thi.ng/shader-ast-stdlib/matrix/lookat.js

Function collection for modular GPGPU / shader programming with @thi.ng/shader-ast

import { M4, V3 } from "@thi.ng/shader-ast/api/types";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import { mat4, vec4 } from "@thi.ng/shader-ast/ast/lit";
import { neg, sub } from "@thi.ng/shader-ast/ast/ops";
import { sym } from "@thi.ng/shader-ast/ast/sym";
import { cross, dot, normalize } from "@thi.ng/shader-ast/builtin/math";
const lookat = defn(M4, "lookat", [V3, V3, V3], (eye, target, up) => {
  let x;
  let y;
  let z;
  return [
    z = sym(normalize(sub(eye, target))),
    x = sym(normalize(cross(up, z))),
    y = sym(normalize(cross(z, x))),
    ret(
      mat4(
        vec4(x, neg(dot(eye, x))),
        vec4(up, neg(dot(eye, y))),
        vec4(z, neg(dot(eye, z))),
        vec4(0, 0, 0, 1)
      )
    )
  ];
});
export {
  lookat
};