Function main

test/browser/webgl_draw_triangle.c:47–117

}

int main() {
  EmscriptenWebGLContextAttributes attr;
  emscripten_webgl_init_context_attributes(&attr);
#ifdef EXPLICIT_SWAP
  attr.explicitSwapControl = 1;
#endif
#ifdef DRAW_FROM_CLIENT_MEMORY
  // This test verifies that drawing from client-side memory when enableExtensionsByDefault==false works.
  attr.enableExtensionsByDefault = 0;
#endif

  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE ctx = emscripten_webgl_create_context("#canvas", &attr);
  emscripten_webgl_make_context_current(ctx);

  static const char vertex_shader[] =
    "attribute vec4 apos;"
    "attribute vec4 acolor;"
    "varying vec4 color;"
    "void main() {"
      "color = acolor;"
      "gl_Position = apos;"
    "}";
  GLuint vs = compile_shader(GL_VERTEX_SHADER, vertex_shader);

  static const char fragment_shader[] =
    "precision lowp float;"
    "varying vec4 color;"
    "void main() {"
      "gl_FragColor = color;"
    "}";
  GLuint fs = compile_shader(GL_FRAGMENT_SHADER, fragment_shader);

  GLuint program = create_program(vs, fs);
  glUseProgram(program);

  static const float pos_and_color[] = {
  //     x,     y, r, g, b
     -0.6f, -0.6f, 1, 0, 0,
      0.6f, -0.6f, 0, 1, 0,
      0.f,   0.6f, 0, 0, 1,
  };

#ifdef DRAW_FROM_CLIENT_MEMORY
  glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 20, pos_and_color);
  glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 20, (void*)(pos_and_color+2));
#else
  GLuint vbo;
  glGenBuffers(1, &vbo);
  glBindBuffer(GL_ARRAY_BUFFER, vbo);
  glBufferData(GL_ARRAY_BUFFER, sizeof(pos_and_color), pos_and_color, GL_STATIC_DRAW);
  glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 20, 0);
  glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 20, (void*)8);
#endif
  glEnableVertexAttribArray(0);
  glEnableVertexAttribArray(1);

  glClearColor(0.3f,0.3f,0.3f,1);
  glClear(GL_COLOR_BUFFER_BIT);