ShaderCache

manage Shader Programs within a context

readyShaderProgram(vertexCode, fragmentCode, geometryCode)

make sure the specified shaders are compiled, linked, and bound

readyShaderProgram(shaders)

make sure the specified shaders are compiled, linked, and bound
will increment the reference count on the shaders if it
needs to keep them around

readyShaderProgram(shaderprogram)

make sure the specified shaders are compiled, linked, and bound

releaseCurrentShaderProgram()

Release the current shader program. Basically go back to
having no shaders loaded. This is useful for old
legacy code that relies on no shaders being loaded.

releaseGraphicsResources(window)

Free up any resources being used by the provided shader

clearLastShaderBound()

Clear the last Shader bound, called by shaders as they release
their graphics resources

Source

index.js

import Md5 from 'spark-md5';

import macro from 'vtk.js/Sources/macros';
import vtkShaderProgram from 'vtk.js/Sources/Rendering/OpenGL/ShaderProgram';

// ----------------------------------------------------------------------------

const SET_GET_FIELDS = [
  'lastShaderProgramBound',
  'context',
  '_openGLRenderWindow',
];

// ----------------------------------------------------------------------------
// vtkShaderCache methods
// ----------------------------------------------------------------------------

function vtkShaderCache(publicAPI, model) {
  // Set our className
  model.classHierarchy.push('vtkShaderCache');

  publicAPI.replaceShaderValues = (VSSource, FSSource, GSSource) => {
    // first handle renaming any Fragment shader inputs
    // if we have a geometry shader. By default fragment shaders
    // assume their inputs come from a Vertex Shader. When we
    // have a Geometry shader we rename the frament shader inputs
    // to come from the geometry shader

    let nFSSource = FSSource;
    if (GSSource.length > 0) {
      nFSSource = vtkShaderProgram.substitute(
        nFSSource,
        'VSOut',
        'GSOut'
      ).result;
    }

    const gl2 = model._openGLRenderWindow.getWebgl2();

    let fragDepthString = '\n';

    let version = '#version 100\n';
    if (gl2) {
      version =
        '#version 300 es\n' +
        '#define attribute in\n' +
        '#define textureCube texture\n' +
        '#define texture2D texture\n' +
        '#define textureCubeLod textureLod\n' +
        '#define texture2DLod textureLod\n';
    } else {
      model.context.getExtension('OES_standard_derivatives');
      if (model.context.getExtension('EXT_frag_depth')) {
        fragDepthString = '#extension GL_EXT_frag_depth : enable\n';
      }
      if (model.context.getExtension('EXT_shader_texture_lod')) {
        fragDepthString +=
          '#extension GL_EXT_shader_texture_lod : enable\n' +
          '#define textureCubeLod textureCubeLodEXT\n' +
          '#define texture2DLod texture2DLodEXT';
      }
    }

    nFSSource = vtkShaderProgram.substitute(nFSSource, '//VTK::System::Dec', [
      `${version}\n`,
      gl2 ? '' : '#extension GL_OES_standard_derivatives : enable\n',
      fragDepthString,
      '#ifdef GL_FRAGMENT_PRECISION_HIGH',
      'precision highp float;',
      'precision highp int;',
      '#else',
      'precision mediump float;',
      'precision mediump int;',
      '#endif',
    ]).result;

    let nVSSource = vtkShaderProgram.substitute(
      VSSource,
      '//VTK::System::Dec',
      [
        `${version}\n`,
        '#ifdef GL_FRAGMENT_PRECISION_HIGH',
        'precision highp float;',
        'precision highp int;',
        '#else',
        'precision mediump float;',
        'precision mediump int;',
        '#endif',
      ]
    ).result;

    if (gl2) {
      nVSSource = vtkShaderProgram.substitute(
        nVSSource,
        'varying',
        'out'
      ).result;
      nFSSource = vtkShaderProgram.substitute(
        nFSSource,
        'varying',
        'in'
      ).result;

      let shaderOutputs = '';
      let outputCount = 0;
      while (nFSSource.includes(`gl_FragData[${outputCount}]`)) {
        nFSSource = vtkShaderProgram.substitute(
          nFSSource,
          `gl_FragData\\[${outputCount}\\]`,
          `fragOutput${outputCount}`
        ).result;
        shaderOutputs += `layout(location = ${outputCount}) out vec4 fragOutput${outputCount};\n`;
        outputCount++;
      }
      nFSSource = vtkShaderProgram.substitute(
        nFSSource,
        '//VTK::Output::Dec',
        shaderOutputs
      ).result;
    }

    // nFSSource = ShaderProgram.substitute(nFSSource, 'gl_FragData\\[0\\]',
    //   'gl_FragColor').result;

    const nGSSource = vtkShaderProgram.substitute(
      GSSource,
      '//VTK::System::Dec',
      version
    ).result;

    return { VSSource: nVSSource, FSSource: nFSSource, GSSource: nGSSource };
  };

  // return NULL if there is an issue
  publicAPI.readyShaderProgramArray = (
    vertexCode,
    fragmentCode,
    geometryCode
  ) => {
    const data = publicAPI.replaceShaderValues(
      vertexCode,
      fragmentCode,
      geometryCode
    );

    const shaderProgram = publicAPI.getShaderProgram(
      data.VSSource,
      data.FSSource,
      data.GSSource
    );

    return publicAPI.readyShaderProgram(shaderProgram);
  };

  publicAPI.readyShaderProgram = (program) => {
    if (!program) {
      return null;
    }

    // compile if needed
    if (!program.getCompiled() && !program.compileShader()) {
      return null;
    }

    // bind if needed
    if (!publicAPI.bindShaderProgram(program)) {
      return null;
    }

    return program;
  };

  publicAPI.getShaderProgram = (vertexCode, fragmentCode, geometryCode) => {
    // compute the MD5 and the check the map
    const hashInput = `${vertexCode}${fragmentCode}${geometryCode}`;
    const result = Md5.hash(hashInput);

    // does it already exist?
    if (!(result in model.shaderPrograms)) {
      // create one
      const sps = vtkShaderProgram.newInstance();
      sps.setContext(model.context);
      sps.getVertexShader().setSource(vertexCode);
      sps.getFragmentShader().setSource(fragmentCode);
      if (geometryCode) {
        sps.getGeometryShader().setSource(geometryCode);
      }
      sps.setMd5Hash(result);
      model.shaderPrograms[result] = sps;
      return sps;
    }

    return model.shaderPrograms[result];
  };

  publicAPI.releaseGraphicsResources = (win) => {
    // NOTE:
    // In the current implementation as of October 26th, if a shader
    // program is created by ShaderCache then it should make sure
    // that it releases the graphics resources used by these programs.
    // It is not wisely for callers to do that since then they would
    // have to loop over all the programs were in use and invoke
    // release graphics resources individually.

    publicAPI.releaseCurrentShaderProgram();

    Object.keys(model.shaderPrograms)
      .map((key) => model.shaderPrograms[key])
      .forEach((sp) => sp.cleanup());
    model.shaderPrograms = {};
  };

  publicAPI.releaseCurrentShaderProgram = () => {
    // release prior shader
    if (model.lastShaderProgramBound) {
      model.lastShaderProgramBound.cleanup();
      model.lastShaderProgramBound = null;
    }
  };

  publicAPI.bindShaderProgram = (program) => {
    if (model.lastShaderProgramBound === program) {
      return 1;
    }

    // release prior program
    if (model.lastShaderProgramBound) {
      model.lastShaderProgramBound.release();
    }
    program.bind();
    model.lastShaderProgramBound = program;
    return 1;
  };
}

// ----------------------------------------------------------------------------
// Object factory
// ----------------------------------------------------------------------------

const DEFAULT_VALUES = {
  lastShaderProgramBound: null,
  shaderPrograms: null,
  context: null,
  // _openGLRenderWindow: null,
};

// ----------------------------------------------------------------------------

export function extend(publicAPI, model, initialValues = {}) {
  Object.assign(model, DEFAULT_VALUES, initialValues);

  // Internal objects
  model.shaderPrograms = {};

  // Build VTK API
  macro.obj(publicAPI, model);
  macro.setGet(publicAPI, model, SET_GET_FIELDS);
  macro.moveToProtected(publicAPI, model, ['openGLRenderWindow']);

  // Object methods
  vtkShaderCache(publicAPI, model);
}

// ----------------------------------------------------------------------------

export const newInstance = macro.newInstance(extend, 'vtkShaderCache');

// ----------------------------------------------------------------------------

export default { newInstance, extend };