getWebGLStub.js

import {
  clone,
  defaultValue,
  defined,
  DeveloperError,
  WebGLConstants,
} from "@cesium/engine";

function getWebGLStub(canvas, options) {
  const stub = clone(WebGLConstants);

  stub.canvas = canvas;
  stub.drawingBufferWidth = Math.max(canvas.width, 1);
  stub.drawingBufferHeight = Math.max(canvas.height, 1);

  stub.activeTexture = noop;
  stub.attachShader = noop;
  stub.bindAttribLocation = noop;
  stub.bindBuffer = noop;
  stub.bindFramebuffer = noop;
  stub.bindRenderbuffer = noop;
  stub.bindTexture = noop;
  stub.blendColor = noop;
  stub.blendEquation = noop;
  stub.blendEquationSeparate = noop;
  stub.blendFunc = noop;
  stub.blendFuncSeparate = noop;
  stub.bufferData = noop;
  stub.bufferSubData = noop;
  stub.checkFramebufferStatus = checkFramebufferStatusStub;
  stub.clear = noop;
  stub.clearColor = noop;
  stub.clearDepth = noop;
  stub.clearStencil = noop;
  stub.colorMask = noop;
  stub.compileShader = noop;
  stub.compressedTexImage2D = noop;
  stub.compressedTexSubImage2D = noop;
  stub.copyTexImage2D = noop;
  stub.copyTexSubImage2D = noop;
  stub.createBuffer = createStub;
  stub.createFramebuffer = createStub;
  stub.createProgram = createStub;
  stub.createRenderbuffer = createStub;
  stub.createShader = createStub;
  stub.createTexture = createStub;
  stub.cullFace = noop;
  stub.deleteBuffer = noop;
  stub.deleteFramebuffer = noop;
  stub.deleteProgram = noop;
  stub.deleteRenderbuffer = noop;
  stub.deleteShader = noop;
  stub.deleteTexture = noop;
  stub.depthFunc = noop;
  stub.depthMask = noop;
  stub.depthRange = noop;
  stub.detachShader = noop;
  stub.disable = noop;
  stub.disableVertexAttribArray = noop;
  stub.drawArrays = noop;
  stub.drawElements = noop;
  stub.enable = noop;
  stub.enableVertexAttribArray = noop;
  stub.finish = noop;
  stub.flush = noop;
  stub.framebufferRenderbuffer = noop;
  stub.framebufferTexture2D = noop;
  stub.frontFace = noop;
  stub.generateMipmap = noop;
  stub.getActiveAttrib = getStub;
  stub.getActiveUniform = getStub;
  stub.getAttachedShaders = getStubWarning;
  stub.getAttribLocation = getStub;
  stub.getBufferParameter = getStubWarning;
  stub.getContextAttributes = getContextAttributesStub(options);
  stub.getError = getErrorStub;
  stub.getExtension = getExtensionStub;
  stub.getFramebufferAttachmentParameter = getStubWarning;
  stub.getParameter = getParameterStub(options);
  stub.getProgramParameter = getProgramParameterStub;
  stub.getProgramInfoLog = getStub;
  stub.getRenderbufferParameter = getStubWarning;
  stub.getShaderParameter = getShaderParameterStub;
  stub.getShaderInfoLog = getStub;
  stub.getShaderPrecisionFormat = getShaderPrecisionStub;
  stub.getShaderSource = getStubWarning;
  stub.getSupportedExtensions = getStubWarning;
  stub.getTexParameter = getStubWarning;
  stub.getUniform = getStub;
  stub.getUniformLocation = getStub;
  stub.getVertexAttrib = getStubWarning;
  stub.getVertexAttribOffset = getStubWarning;
  stub.hint = noop;
  stub.isBuffer = getStubWarning;
  stub.isContextLost = getStubWarning;
  stub.isEnabled = getStubWarning;
  stub.isFramebuffer = getStubWarning;
  stub.isProgram = getStubWarning;
  stub.isRenderbuffer = getStubWarning;
  stub.isShader = getStubWarning;
  stub.isTexture = getStubWarning;
  stub.lineWidth = noop;
  stub.linkProgram = noop;
  stub.pixelStorei = noop;
  stub.polygonOffset = noop;
  stub.readPixels = readPixelsStub;
  stub.renderbufferStorage = noop;
  stub.sampleCoverage = noop;
  stub.scissor = noop;
  stub.shaderSource = noop;
  stub.stencilFunc = noop;
  stub.stencilFuncSeparate = noop;
  stub.stencilMask = noop;
  stub.stencilMaskSeparate = noop;
  stub.stencilOp = noop;
  stub.stencilOpSeparate = noop;
  stub.texParameterf = noop;
  stub.texParameteri = noop;
  stub.texImage2D = noop;
  stub.texSubImage2D = noop;
  stub.uniform1f = noop;
  stub.uniform1fv = noop;
  stub.uniform1i = noop;
  stub.uniform1iv = noop;
  stub.uniform2f = noop;
  stub.uniform2fv = noop;
  stub.uniform2i = noop;
  stub.uniform2iv = noop;
  stub.uniform3f = noop;
  stub.uniform3fv = noop;
  stub.uniform3i = noop;
  stub.uniform3iv = noop;
  stub.uniform4f = noop;
  stub.uniform4fv = noop;
  stub.uniform4i = noop;
  stub.uniform4iv = noop;
  stub.uniformMatrix2fv = noop;
  stub.uniformMatrix3fv = noop;
  stub.uniformMatrix4fv = noop;
  stub.useProgram = noop;
  stub.validateProgram = noop;
  stub.vertexAttrib1f = noop;
  stub.vertexAttrib1fv = noop;
  stub.vertexAttrib2f = noop;
  stub.vertexAttrib2fv = noop;
  stub.vertexAttrib3f = noop;
  stub.vertexAttrib3fv = noop;
  stub.vertexAttrib4f = noop;
  stub.vertexAttrib4fv = noop;
  stub.vertexAttribPointer = noop;
  stub.viewport = noop;

  return stub;
}

// ANGLE_instanced_arrays
const instancedArraysStub = {
  drawElementsInstancedANGLE: noop,
  drawArraysInstancedANGLE: noop,
  vertexAttribDivisorANGLE: noop,
};

function noop() {}

function createStub() {
  return {};
}

function getStub() {
  return {};
}

function getStubWarning() {
  //>>includeStart('debug', pragmas.debug);
  throw new DeveloperError(
    "A stub for this get/is function is not defined.  Can it use getStub() or does it need a new one?"
  );
  //>>includeEnd('debug');
}

function checkFramebufferStatusStub(target) {
  return WebGLConstants.FRAMEBUFFER_COMPLETE;
}

function getContextAttributesStub(options) {
  const contextAttributes = {
    alpha: defaultValue(options.alpha, true),
    depth: defaultValue(options.depth, true),
    stencil: defaultValue(options.stencil, false),
    antialias: defaultValue(options.antialias, true),
    premultipliedAlpha: defaultValue(options.premultipliedAlpha, true),
    preserveDrawingBuffer: defaultValue(options.preserveDrawingBuffer, false),
    powerPreference: defaultValue(options.powerPreference, false),
    failIfMajorPerformanceCaveat: defaultValue(
      options.failIfMajorPerformanceCaveat,
      false
    ),
  };

  return function () {
    return contextAttributes;
  };
}

function getErrorStub() {
  return WebGLConstants.NO_ERROR;
}

function getExtensionStub(name) {
  // Many 3D Tiles tests rely on instanced arrays
  if (name === "ANGLE_instanced_arrays") {
    return instancedArraysStub;
  }

  // Voxel tests rely on floating point textures
  if (name === "OES_texture_float") {
    return {};
  }

  // No other extensions are stubbed.
  return null;
}

function getParameterStub(options) {
  // These are not the minimum maximum; instead, they are typical maximums.
  const parameterStubValues = {};
  parameterStubValues[WebGLConstants.STENCIL_BITS] = options.stencil ? 8 : 0;
  parameterStubValues[WebGLConstants.MAX_COMBINED_TEXTURE_IMAGE_UNITS] = 32;
  parameterStubValues[WebGLConstants.MAX_CUBE_MAP_TEXTURE_SIZE] = 16384;
  parameterStubValues[WebGLConstants.MAX_FRAGMENT_UNIFORM_VECTORS] = 1024;
  parameterStubValues[WebGLConstants.MAX_TEXTURE_IMAGE_UNITS] = 16;
  parameterStubValues[WebGLConstants.MAX_RENDERBUFFER_SIZE] = 16384;
  parameterStubValues[WebGLConstants.MAX_TEXTURE_SIZE] = 16384;
  parameterStubValues[WebGLConstants.MAX_VARYING_VECTORS] = 30;
  parameterStubValues[WebGLConstants.MAX_VERTEX_ATTRIBS] = 16;
  parameterStubValues[WebGLConstants.MAX_VERTEX_TEXTURE_IMAGE_UNITS] = 16;
  parameterStubValues[WebGLConstants.MAX_VERTEX_UNIFORM_VECTORS] = 4096;
  parameterStubValues[WebGLConstants.ALIASED_LINE_WIDTH_RANGE] = [1, 1];
  parameterStubValues[WebGLConstants.ALIASED_POINT_SIZE_RANGE] = [1, 1024];
  parameterStubValues[WebGLConstants.MAX_VIEWPORT_DIMS] = [16384, 16384];
  parameterStubValues[WebGLConstants.MAX_TEXTURE_MAX_ANISOTROPY_EXT] = 16; // Assuming extension
  parameterStubValues[WebGLConstants.MAX_DRAW_BUFFERS] = 8; // Assuming extension
  parameterStubValues[WebGLConstants.MAX_COLOR_ATTACHMENTS] = 8; // Assuming extension
  parameterStubValues[WebGLConstants.MAX_SAMPLES] = 8; // Assuming WebGL2

  return function (pname) {
    const value = parameterStubValues[pname];

    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError(
        `A WebGL parameter stub for ${pname} is not defined. Add it.`
      );
    }
    //>>includeEnd('debug');

    return value;
  };
}

function getProgramParameterStub(program, pname) {
  if (
    pname === WebGLConstants.LINK_STATUS ||
    pname === WebGLConstants.VALIDATE_STATUS
  ) {
    return true;
  }

  if (
    pname === WebGLConstants.ACTIVE_UNIFORMS ||
    pname === WebGLConstants.ACTIVE_ATTRIBUTES
  ) {
    return 0;
  }

  //>>includeStart('debug', pragmas.debug);
  throw new DeveloperError(
    `A WebGL parameter stub for ${pname} is not defined. Add it.`
  );
  //>>includeEnd('debug');
}

function getShaderParameterStub(shader, pname) {
  //>>includeStart('debug', pragmas.debug);
  if (pname !== WebGLConstants.COMPILE_STATUS) {
    throw new DeveloperError(
      `A WebGL parameter stub for ${pname} is not defined. Add it.`
    );
  }
  //>>includeEnd('debug');

  return true;
}

function getShaderPrecisionStub(shadertype, precisiontype) {
  //>>includeStart('debug', pragmas.debug);
  if (shadertype !== WebGLConstants.FRAGMENT_SHADER) {
    throw new DeveloperError(
      "getShaderPrecision only has a stub for FRAGMENT_SHADER. Update it."
    );
  }

  if (
    precisiontype !== WebGLConstants.HIGH_FLOAT &&
    precisiontype !== WebGLConstants.HIGH_INT
  ) {
    throw new DeveloperError(
      "getShaderPrecision only has a stub for HIGH_FLOAT and HIGH_INT. Update it."
    );
  }
  //>>includeEnd('debug');

  if (precisiontype === WebGLConstants.HIGH_FLOAT) {
    return {
      rangeMin: 127,
      rangeMax: 127,
      precision: 23,
    };
  }

  // HIGH_INT
  return {
    rangeMin: 31,
    rangeMax: 30,
    precision: 0,
  };
}

function readPixelsStub(x, y, width, height, format, type, pixels) {
  return [0, 0, 0, 0];
}
export default getWebGLStub;