Function main

test/browser/webgl_sample_query.c:64–136

}

int main() {
  EmscriptenWebGLContextAttributes attrs;
  emscripten_webgl_init_context_attributes(&attrs);

  attrs.enableExtensionsByDefault = 1;
  attrs.majorVersion = 2;
  attrs.minorVersion = 0;

  /* Skip WebGL 2 tests if not supported */
  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context("#canvas", &attrs);
  if (!context) {
    printf("Skipped: WebGL 2 is not supported.\n");
    return 0;
  }
  emscripten_webgl_make_context_current(context);

  /* Generate a query */
  GL_CALL(glGenQueries(2, &sampleQuery));
  assert(sampleQuery);

  /* Begin it */
  GL_CALL(glBeginQuery(GL_ANY_SAMPLES_PASSED, sampleQuery));

  /* Now, `sampleQuery` should be a query */
  bool isQuery = false;
  GL_CALL(isQuery = glIsQuery(sampleQuery));
  assert(isQuery);

  /* Do a draw to actually have something in the queue */
  GLuint vert = compile_shader(GL_VERTEX_SHADER,
    "#version 300 es\n"
    "in vec4 position;\n"
    "void main() {\n"
    "  gl_Position = position;\n"
    "}\n");
  GLuint frag = compile_shader(GL_FRAGMENT_SHADER,
    "#version 300 es\n"
    "precision lowp float;\n"
    "out vec4 color;\n"
    "void main() {\n"
    "  color = vec4(1.0, 0.3, 0.1, 1.0);\n"
    "}\n");
  GLuint program = create_program(vert, frag);
  GL_CALL(glUseProgram(program));
  const float positions[] = {
    -0.5f, -0.5f, 0.0f,
     0.5f, -0.5f, 0.0f,
     0.0f,  0.5f, 0.0f
  };
  GLuint vertices;
  GL_CALL(glGenBuffers(1, &vertices));
  GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vertices));
  GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW));
  GL_CALL(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 12, 0));
  GL_CALL(glEnableVertexAttribArray(0));
  GL_CALL(glClearColor(0.5f, 0.7f, 0.9f, 1.0f));
  GL_CALL(glClear(GL_COLOR_BUFFER_BIT));
  GL_CALL(glDrawArrays(GL_TRIANGLES, 0, 3));