text: // Calls glDrawElements() the number of times specified by
  // ITERATIONS. Should draw a checkerboard on the screen after
  // a few seconds.
  //
  // Ported from a Java version by Google.
  
  #include <EGL/egl.h>
  #include <GLES/gl.h>
  #include <GLES/glext.h>
  
  #include <WindowSurface.h>
  #include <EGLUtils.h>
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <math.h>
  
  using namespace android;
  
  EGLDisplay eglDisplay;
  EGLSurface eglSurface;
  EGLContext eglContext;
  GLuint texture;
  
  #define FIXED_ONE 0x10000
  #define ITERATIONS 50
  
  int init_gl_surface(const WindowSurface&);
  void free_gl_surface(void);
  void init_scene(void);
  void render(int quads);
  void create_texture(void);
  int readTimer(void);
  
  static void gluLookAt(float eyeX, float eyeY, float eyeZ,
          float centerX, float centerY, float centerZ, float upX, float upY,
          float upZ)
  {
      // See the OpenGL GLUT documentation for gluLookAt for a description
      // of the algorithm. We implement it in a straightforward way:
  
      float fx = centerX - eyeX;
      float fy = centerY - eyeY;
      float fz = centerZ - eyeZ;
  
      // Normalize f
      float rlf = 1.0f / sqrtf(fx*fx + fy*fy + fz*fz);
      fx *= rlf;
      fy *= rlf;
      fz *= rlf;
  
      // Normalize up
      float rlup = 1.0f / sqrtf(upX*upX + upY*upY + upZ*upZ);
      upX *= rlup;
      upY *= rlup;
      upZ *= rlup;
  
      // compute s = f x up (x means "cross product")
  
      float sx = fy * upZ - fz * upY;
      float sy = fz * upX - fx * upZ;
      float sz = fx * upY - fy * upX;
  
      // compute u = s x f
      float ux = sy * fz - sz * fy;
      float uy = sz * fx - sx * fz;
      float uz = sx * fy - sy * fx;
  
      float m[16] ;
      m[0] = sx;
      m[1] = ux;
      m[2] = -fx;
      m[3] = 0.0f;
  
      m[4] = sy;
      m[5] = uy;
      m[6] = -fy;
      m[7] = 0.0f;
  
      m[8] = sz;
      m[9] = uz;
      m[10] = -fz;
      m[11] = 0.0f;
  
      m[12] = 0.0f;
      m[13] = 0.0f;
      m[14] = 0.0f;
      m[15] = 1.0f;
  
      glMultMatrixf(m);
      glTranslatef(-eyeX, -eyeY, -eyeZ);
  }
  
  int main(int argc, char **argv)
  {
      int q;
      int start, end;
  
      printf("Initializing EGL...\n");
  
      WindowSurface windowSurface;
      if(!init_gl_surface(windowSurface))
      {
          printf("GL initialisation failed - exiting\n");
          return 0;
      }
  
      init_scene();
  
      create_texture();
  
      printf("Start test...\n");
  
      render(argc==2 ? atoi(argv[1]) : ITERATIONS);
  
      free_gl_surface();
  
      return 0;
  }
  
  int init_gl_surface(const WindowSurface& windowSurface)
  {
      EGLint numConfigs = 1;
      EGLConfig myConfig = {0};
      EGLint attrib[] =
      {
              EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
              EGL_DEPTH_SIZE,     16,
              EGL_NONE
      };
  
      if ( (eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY)) == EGL_NO_DISPLAY )
      {
          printf("eglGetDisplay failed\n");
          return 0;
      }
  
      if ( eglInitialize(eglDisplay, NULL, NULL) != EGL_TRUE )
      {
          printf("eglInitialize failed\n");
          return 0;
      }
  
      EGLNativeWindowType window = windowSurface.getSurface();
      EGLUtils::selectConfigForNativeWindow(eglDisplay, attrib, window, &myConfig);
  
      if ( (eglSurface = eglCreateWindowSurface(eglDisplay, myConfig,
              window, 0)) == EGL_NO_SURFACE )
      {
          printf("eglCreateWindowSurface failed\n");
          return 0;
      }
  
      if ( (eglContext = eglCreateContext(eglDisplay, myConfig, 0, 0)) == EGL_NO_CONTEXT )
      {
          printf("eglCreateContext failed\n");
          return 0;
      }
  
      if ( eglMakeCurrent(eglDisplay, eglSurface, eglSurface, eglContext) != EGL_TRUE )
      {
          printf("eglMakeCurrent failed\n");
          return 0;
      }
  
      return 1;
  }
  
  void free_gl_surface(void)
  {
      if (eglDisplay != EGL_NO_DISPLAY)
      {
          eglMakeCurrent( EGL_NO_DISPLAY, EGL_NO_SURFACE,
                  EGL_NO_SURFACE, EGL_NO_CONTEXT );
          eglDestroyContext( eglDisplay, eglContext );
          eglDestroySurface( eglDisplay, eglSurface );
          eglTerminate( eglDisplay );
          eglDisplay = EGL_NO_DISPLAY;
      }
  }
  
  void init_scene(void)
  {
      glDisable(GL_DITHER);
      glEnable(GL_CULL_FACE);
  
      float ratio = 320.0f / 480.0f;
      glViewport(0, 0, 320, 480);
  
      glMatrixMode(GL_PROJECTION);
      glLoadIdentity();
      glFrustumf(-ratio, ratio, -1, 1, 1, 10);
  
      glMatrixMode(GL_MODELVIEW);
      glLoadIdentity();
      gluLookAt(
              0, 0, 3,  // eye
              0, 0, 0,  // center
              0, 1, 0); // up
  
      glEnable(GL_TEXTURE_2D);
      glEnableClientState(GL_VERTEX_ARRAY);
      glEnableClientState(GL_TEXTURE_COORD_ARRAY);
  }
  
  void create_texture(void)
  {
      const unsigned int on = 0xff0000ff;
      const unsigned int off = 0xffffffff;
      const unsigned int pixels[] =
      {
              on, off, on, off, on, off, on, off,
              off, on, off, on, off, on, off, on,
              on, off, on, off, on, off, on, off,
              off, on, off, on, off, on, off, on,
              on, off, on, off, on, off, on, off,
              off, on, off, on, off, on, off, on,
              on, off, on, off, on, off, on, off,
              off, on, off, on, off, on, off, on,
      };
      glGenTextures(1, &texture);
      glBindTexture(GL_TEXTURE_2D, texture);
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 8, 8, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
      glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
      glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
      glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
  }
  
  void render(int quads)
  {
      int i, j;
  
      const GLfloat vertices[] = {
              -1,  -1,  0,
               1,  -1,  0,
               1,   1,  0,
              -1,   1,  0
      };
  
      const GLfixed texCoords[] = {
              0,            0,
              FIXED_ONE,    0,
              FIXED_ONE,    FIXED_ONE,
              0,            FIXED_ONE
      };
  
      const GLushort quadIndices[] = { 0, 1, 2,  0, 2, 3 };
  
  
      GLushort* indices = (GLushort*)malloc(quads*sizeof(quadIndices));
      for (i=0 ; i<quads ; i++)
          memcpy(indices+(sizeof(quadIndices)/sizeof(indices[0]))*i, quadIndices, sizeof(quadIndices));
  
      glVertexPointer(3, GL_FLOAT, 0, vertices);
      glTexCoordPointer(2, GL_FIXED, 0, texCoords);
  
      // make sure to do a couple eglSwapBuffers to make sure there are
      // no problems with the very first ones (who knows)
      glClearColor(0.4, 0.4, 0.4, 0.4);
      glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
      eglSwapBuffers(eglDisplay, eglSurface);
      glClearColor(0.6, 0.6, 0.6, 0.6);
      glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
      eglSwapBuffers(eglDisplay, eglSurface);
      glClearColor(1.0, 1.0, 1.0, 1.0);
  
      for (j=0 ; j<10 ; j++) {
          printf("loop %d / 10 (%d quads / loop)\n", j, quads);
  
          int nelem = sizeof(quadIndices)/sizeof(quadIndices[0]);
          glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
          glDrawElements(GL_TRIANGLES, nelem*quads, GL_UNSIGNED_SHORT, indices);
          eglSwapBuffers(eglDisplay, eglSurface);
      }
  
      free(indices);
  }
  
  