@giro3d/giro3d/renderer/shader/ShaderUtils.js

A JS/WebGL framework for 3D geospatial data visualization

/* babel-plugin-inline-import './chunk/giro3d_precision_qualifiers.glsl' */
const PrecisionQualifier = "precision highp float;\nprecision highp int;";
const rePosition = new RegExp('gl_Position.*(?![^]*gl_Position)');
const reMain = new RegExp('[^\\w]*main[^\\w]*(void)?[^\\w]*{');
export default {
  patchMaterialForLogDepthSupport(material) {
    // Check if the shader does not already use the log depth buffer
    if (material.vertexShader.indexOf('USE_LOGDEPTHBUF') !== -1 || material.vertexShader.indexOf('logdepthbuf_pars_vertex') !== -1) {
      return;
    }

    // Add vertex shader log depth buffer header
    material.vertexShader = `#include <logdepthbuf_pars_vertex>\n#define EPSILON 1e-6\n${material.vertexShader}`;
    // Add log depth buffer code snippet after last gl_Position modification
    let re = rePosition.exec(material.vertexShader);
    if (re && re.length > 0) {
      const idx = re[0].length + re.index;
      material.vertexShader = `${material.vertexShader.slice(0, idx)}\n#include <logdepthbuf_vertex>\n${material.vertexShader.slice(idx)}`;
    }

    // Add fragment shader log depth buffer header
    material.fragmentShader = `${PrecisionQualifier}\n#include <logdepthbuf_pars_fragment>\n${material.fragmentShader}`;
    // Add log depth buffer code snippet at the first line of the main function
    re = reMain.exec(material.fragmentShader);
    if (re && re.length > 0) {
      const idx = re[0].length + re.index;
      material.fragmentShader = `${material.fragmentShader.slice(0, idx)}\n#include <logdepthbuf_fragment>\n${material.fragmentShader.slice(idx)}`;
    }
    material.defines = {
      USE_LOGDEPTHBUF: 1,
      USE_LOGDEPTHBUF_EXT: 1
    };
  }
};