@thi.ng/webgl/draw.js

WebGL & GLSL abstraction layer

import { isArray } from "@thi.ng/checks/is-array";
import { isGL2Context } from "./checks.js";
import { error } from "./error.js";
import { bindTextures, unbindTextures } from "./texture.js";
const draw = (specs, opts = {}) => {
  const _specs = isArray(specs) ? specs : [specs];
  for (let i = 0, n = _specs.length; i < n; i++) {
    const spec = _specs[i];
    const indices = spec.indices;
    const gl = spec.shader.gl;
    opts.bindTex !== false && bindTextures(spec.textures);
    opts.shaderState !== false && spec.shader.prepareState();
    opts.bindShader !== false && spec.shader.bind(spec);
    if (indices?.buffer) {
      indices.buffer.bind();
      if (spec.instances) {
        __drawInstanced(gl, spec);
      } else {
        gl.drawElements(
          spec.mode,
          spec.num,
          indices.data instanceof Uint32Array ? gl.UNSIGNED_INT : gl.UNSIGNED_SHORT,
          0
        );
      }
    } else {
      if (spec.instances) {
        __drawInstanced(gl, spec);
      } else {
        gl.drawArrays(spec.mode, 0, spec.num);
      }
    }
    opts.unbindShader !== false && spec.shader.unbind(null);
    opts.unbindTex && unbindTextures(spec.textures);
  }
};
const __drawInstanced = (gl, spec) => {
  const isGL2 = isGL2Context(gl);
  const ext = !isGL2 ? gl.getExtension("ANGLE_instanced_arrays") : void 0;
  if (!(isGL2 || ext)) {
    error("instancing not supported");
  }
  const sattribs = spec.shader.attribs;
  const iattribs = spec.instances.attribs;
  spec.shader.bindAttribs(iattribs);
  for (let id in iattribs) {
    const attr = sattribs[id];
    if (attr) {
      let div = iattribs[id].divisor;
      div = div !== void 0 ? div : 1;
      isGL2 ? gl.vertexAttribDivisor(
        attr.loc,
        div
      ) : ext.vertexAttribDivisorANGLE(attr.loc, div);
    }
  }
  if (spec.indices) {
    const type = spec.indices.data instanceof Uint32Array ? gl.UNSIGNED_INT : gl.UNSIGNED_SHORT;
    isGL2 ? gl.drawElementsInstanced(
      spec.mode,
      spec.num,
      type,
      0,
      spec.instances.num
    ) : ext.drawElementsInstancedANGLE(
      spec.mode,
      spec.num,
      type,
      0,
      spec.instances.num
    );
  } else {
    isGL2 ? gl.drawArraysInstanced(
      spec.mode,
      0,
      spec.num,
      spec.instances.num
    ) : ext.drawArraysInstancedANGLE(
      spec.mode,
      0,
      spec.num,
      spec.instances.num
    );
  }
  for (let id in iattribs) {
    const attr = sattribs[id];
    attr && (isGL2 ? gl.vertexAttribDivisor(attr.loc, 0) : ext.vertexAttribDivisorANGLE(attr.loc, 0));
  }
  spec.shader.unbind(null);
};
export {
  draw
};