/*
* Copyright (c) 2012 Broadcom Europe Ltd
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License.  You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*
* A rotating cube rendered with OpenGL|ES. Three images used as textures on the cube faces.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <assert.h>
#include <unistd.h>

#include "bcm_host.h"

#include "GLES/gl.h"
#include "EGL/egl.h"
#include "EGL/eglext.h"

#include "cube_texture_and_coords.h"

#define PATH "./"

#define IMAGE_SIZE 128

#ifndef M_PI
   #define M_PI 3.141592654
#endif


typedef struct
{
   uint32_t screen_width;
   uint32_t screen_height;
// OpenGL|ES objects
   EGLDisplay display;
   EGLSurface surface;
   EGLContext context;
   GLuint tex[6];
// model rotation vector and direction
   GLfloat rot_angle_x_inc;
   GLfloat rot_angle_y_inc;
   GLfloat rot_angle_z_inc;
// current model rotation angles
   GLfloat rot_angle_x;
   GLfloat rot_angle_y;
   GLfloat rot_angle_z;
// current distance from camera
   GLfloat distance;
   GLfloat distance_inc;
// pointers to texture buffers
   char *tex_buf1;
   char *tex_buf2;
   char *tex_buf3;
} CUBE_STATE_T;

static void init_ogl(CUBE_STATE_T *state);
static void init_model_proj(CUBE_STATE_T *state);
static void reset_model(CUBE_STATE_T *state);
static GLfloat inc_and_wrap_angle(GLfloat angle, GLfloat angle_inc);
static GLfloat inc_and_clip_distance(GLfloat distance, GLfloat distance_inc);
static void redraw_scene(CUBE_STATE_T *state);
static void update_model(CUBE_STATE_T *state);
static void init_textures(CUBE_STATE_T *state);
static void load_tex_images(CUBE_STATE_T *state);
static void exit_func(void);
static volatile int terminate;
static CUBE_STATE_T _state, *state=&_state;


/***********************************************************
 * Name: init_ogl
 *
 * Arguments:
 *       CUBE_STATE_T *state - holds OGLES model info
 *
 * Description: Sets the display, OpenGL|ES context and screen stuff
 *
 * Returns: void
 *
 ***********************************************************/
static void init_ogl(CUBE_STATE_T *state)
{
   int32_t success = 0;
   EGLBoolean result;
   EGLint num_config;

   static EGL_DISPMANX_WINDOW_T nativewindow;

   DISPMANX_ELEMENT_HANDLE_T dispman_element;
   DISPMANX_DISPLAY_HANDLE_T dispman_display;
   DISPMANX_UPDATE_HANDLE_T dispman_update;
   VC_RECT_T dst_rect;
   VC_RECT_T src_rect;

   static const EGLint attribute_list[] =
   {
      EGL_RED_SIZE, 8,
      EGL_GREEN_SIZE, 8,
      EGL_BLUE_SIZE, 8,
      EGL_ALPHA_SIZE, 8,
      EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
      EGL_NONE
   };

   EGLConfig config;

   // get an EGL display connection
   state->display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
   assert(state->display!=EGL_NO_DISPLAY);

   // initialize the EGL display connection
   result = eglInitialize(state->display, NULL, NULL);
   assert(EGL_FALSE != result);

   // get an appropriate EGL frame buffer configuration
   result = eglChooseConfig(state->display, attribute_list, &config, 1, &num_config);
   assert(EGL_FALSE != result);

   // create an EGL rendering context
   state->context = eglCreateContext(state->display, config, EGL_NO_CONTEXT, NULL);
   assert(state->context!=EGL_NO_CONTEXT);

   // create an EGL window surface
   success = graphics_get_display_size(0 /* LCD */, &state->screen_width, &state->screen_height);
   assert( success >= 0 );

   dst_rect.x = 0;
   dst_rect.y = 0;
   dst_rect.width = state->screen_width;
   dst_rect.height = state->screen_height;

   src_rect.x = 0;
   src_rect.y = 0;
   src_rect.width = state->screen_width << 16;
   src_rect.height = state->screen_height << 16;

   dispman_display = vc_dispmanx_display_open( 0 /* LCD */);
   dispman_update = vc_dispmanx_update_start( 0 );

   dispman_element = vc_dispmanx_element_add ( dispman_update, dispman_display,
      0/*layer*/, &dst_rect, 0/*src*/,
      &src_rect, DISPMANX_PROTECTION_NONE, 0 /*alpha*/, 0/*clamp*/, 0/*transform*/);

   nativewindow.element = dispman_element;
   nativewindow.width = state->screen_width;
   nativewindow.height = state->screen_height;
   vc_dispmanx_update_submit_sync( dispman_update );

   state->surface = eglCreateWindowSurface( state->display, config, &nativewindow, NULL );
   assert(state->surface != EGL_NO_SURFACE);

   // connect the context to the surface
   result = eglMakeCurrent(state->display, state->surface, state->surface, state->context);
   assert(EGL_FALSE != result);

   // Set background color and clear buffers
   glClearColor(0.15f, 0.25f, 0.35f, 1.0f);
   glClear( GL_COLOR_BUFFER_BIT );
   glClear( GL_DEPTH_BUFFER_BIT );
   glShadeModel(GL_FLAT);

   // Enable back face culling.
   glEnable(GL_CULL_FACE);
}

/***********************************************************
 * Name: init_model_proj
 *
 * Arguments:
 *       CUBE_STATE_T *state - holds OGLES model info
 *
 * Description: Sets the OpenGL|ES model to default values
 *
 * Returns: void
 *
 ***********************************************************/
static void init_model_proj(CUBE_STATE_T *state)
{
   float nearp = 1.0f;
   float farp = 500.0f;
   float hht;
   float hwd;

   glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST );

   glViewport(0, 0, (GLsizei)state->screen_width, (GLsizei)state->screen_height);

   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();

   hht = nearp * (float)tan(45.0 / 2.0 / 180.0 * M_PI);
   hwd = hht * (float)state->screen_width / (float)state->screen_height;

   glFrustumf(-hwd, hwd, -hht, hht, nearp, farp);

   glEnableClientState( GL_VERTEX_ARRAY );
   glVertexPointer( 3, GL_BYTE, 0, quadx );

   glEnableClientState( GL_COLOR_ARRAY );
   glColorPointer(4, GL_FLOAT, 0, colorsf);

   reset_model(state);
}

/***********************************************************
 * Name: reset_model
 *
 * Arguments:
 *       CUBE_STATE_T *state - holds OGLES model info
 *
 * Description: Resets the Model projection and rotation direction
 *
 * Returns: void
 *
 ***********************************************************/
static void reset_model(CUBE_STATE_T *state)
{
   // reset model position
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glTranslatef(0.f, 0.f, -50.f);

   // reset model rotation
   state->rot_angle_x = 45.f; state->rot_angle_y = 30.f; state->rot_angle_z = 0.f;
   state->rot_angle_x_inc = 0.5f; state->rot_angle_y_inc = 0.5f; state->rot_angle_z_inc = 0.f;
   state->distance = 40.f;
}

/***********************************************************
 * Name: update_model
 *
 * Arguments:
 *       CUBE_STATE_T *state - holds OGLES model info
 *
 * Description: Updates model projection to current position/rotation
 *
 * Returns: void
 *
 ***********************************************************/
static void update_model(CUBE_STATE_T *state)
{
   // update position
   state->rot_angle_x = inc_and_wrap_angle(state->rot_angle_x, state->rot_angle_x_inc);
   state->rot_angle_y = inc_and_wrap_angle(state->rot_angle_y, state->rot_angle_y_inc);
   state->rot_angle_z = inc_and_wrap_angle(state->rot_angle_z, state->rot_angle_z_inc);
   state->distance    = inc_and_clip_distance(state->distance, state->distance_inc);

   glLoadIdentity();
   // move camera back to see the cube
   glTranslatef(0.f, 0.f, -state->distance);

   // Rotate model to new position
   glRotatef(state->rot_angle_x, 1.f, 0.f, 0.f);
   glRotatef(state->rot_angle_y, 0.f, 1.f, 0.f);
   glRotatef(state->rot_angle_z, 0.f, 0.f, 1.f);
}

/***********************************************************
 * Name: inc_and_wrap_angle
 *
 * Arguments:
 *       GLfloat angle     current angle
 *       GLfloat angle_inc angle increment
 *
 * Description:   Increments or decrements angle by angle_inc degrees
 *                Wraps to 0 at 360 deg.
 *
 * Returns: new value of angle
 *
 ***********************************************************/
static GLfloat inc_and_wrap_angle(GLfloat angle, GLfloat angle_inc)
{
   angle += angle_inc;

   if (angle >= 360.0)
      angle -= 360.f;
   else if (angle <=0)
      angle += 360.f;

   return angle;
}

/***********************************************************
 * Name: inc_and_clip_distance
 *
 * Arguments:
 *       GLfloat distance     current distance
 *       GLfloat distance_inc distance increment
 *
 * Description:   Increments or decrements distance by distance_inc units
 *                Clips to range
 *
 * Returns: new value of angle
 *
 ***********************************************************/
static GLfloat inc_and_clip_distance(GLfloat distance, GLfloat distance_inc)
{
   distance += distance_inc;

   if (distance >= 120.0f)
      distance = 120.f;
   else if (distance <= 40.0f)
      distance = 40.0f;

   return distance;
}

/***********************************************************
 * Name: redraw_scene
 *
 * Arguments:
 *       CUBE_STATE_T *state - holds OGLES model info
 *
 * Description:   Draws the model and calls eglSwapBuffers
 *                to render to screen
 *
 * Returns: void
 *
 ***********************************************************/
static void redraw_scene(CUBE_STATE_T *state)
{
   // Start with a clear screen
   glClear( GL_COLOR_BUFFER_BIT );
   glMatrixMode(GL_MODELVIEW);

   glEnable(GL_TEXTURE_2D);
   glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

   // Draw first (front) face:
   // Bind texture surface to current vertices
   glBindTexture(GL_TEXTURE_2D, state->tex[0]);

   // Need to rotate textures - do this by rotating each cube face
   glRotatef(270.f, 0.f, 0.f, 1.f ); // front face normal along z axis

   // draw first 4 vertices
   glDrawArrays( GL_TRIANGLE_STRIP, 0, 4);

   // same pattern for other 5 faces - rotation chosen to make image orientation 'nice'
   glBindTexture(GL_TEXTURE_2D, state->tex[1]);
   glRotatef(90.f, 0.f, 0.f, 1.f ); // back face normal along z axis
   glDrawArrays( GL_TRIANGLE_STRIP, 4, 4);

   glBindTexture(GL_TEXTURE_2D, state->tex[2]);
   glRotatef(90.f, 1.f, 0.f, 0.f ); // left face normal along x axis
   glDrawArrays( GL_TRIANGLE_STRIP, 8, 4);

   glBindTexture(GL_TEXTURE_2D, state->tex[3]);
   glRotatef(90.f, 1.f, 0.f, 0.f ); // right face normal along x axis
   glDrawArrays( GL_TRIANGLE_STRIP, 12, 4);

   glBindTexture(GL_TEXTURE_2D, state->tex[4]);
   glRotatef(270.f, 0.f, 1.f, 0.f ); // top face normal along y axis
   glDrawArrays( GL_TRIANGLE_STRIP, 16, 4);

   glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

   glBindTexture(GL_TEXTURE_2D, state->tex[5]);
   glRotatef(90.f, 0.f, 1.f, 0.f ); // bottom face normal along y axis
   glDrawArrays( GL_TRIANGLE_STRIP, 20, 4);

   glDisable(GL_TEXTURE_2D);

   eglSwapBuffers(state->display, state->surface);
}

/***********************************************************
 * Name: init_textures
 *
 * Arguments:
 *       CUBE_STATE_T *state - holds OGLES model info
 *
 * Description:   Initialise OGL|ES texture surfaces to use image
 *                buffers
 *
 * Returns: void
 *
 ***********************************************************/
static void init_textures(CUBE_STATE_T *state)
{
   // load three texture buffers but use them on six OGL|ES texture surfaces
   load_tex_images(state);
   glGenTextures(6, &state->tex[0]);

   // setup first texture
   glBindTexture(GL_TEXTURE_2D, state->tex[0]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, IMAGE_SIZE, IMAGE_SIZE, 0,
                GL_RGB, GL_UNSIGNED_BYTE, state->tex_buf1);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, (GLfloat)GL_NEAREST);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, (GLfloat)GL_NEAREST);

   // setup second texture - reuse first image
   glBindTexture(GL_TEXTURE_2D, state->tex[1]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, IMAGE_SIZE, IMAGE_SIZE, 0,
                GL_RGB, GL_UNSIGNED_BYTE, state->tex_buf1);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, (GLfloat)GL_NEAREST);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, (GLfloat)GL_NEAREST);

   // third texture
   glBindTexture(GL_TEXTURE_2D, state->tex[2]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, IMAGE_SIZE, IMAGE_SIZE, 0,
                GL_RGB, GL_UNSIGNED_BYTE, state->tex_buf2);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, (GLfloat)GL_NEAREST);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, (GLfloat)GL_NEAREST);

   // fourth texture  - reuse second image
   glBindTexture(GL_TEXTURE_2D, state->tex[3]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, IMAGE_SIZE, IMAGE_SIZE, 0,
                GL_RGB, GL_UNSIGNED_BYTE, state->tex_buf2);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, (GLfloat)GL_NEAREST);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, (GLfloat)GL_NEAREST);

   //fifth texture
   glBindTexture(GL_TEXTURE_2D, state->tex[4]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, IMAGE_SIZE, IMAGE_SIZE, 0,
                GL_RGB, GL_UNSIGNED_BYTE, state->tex_buf3);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, (GLfloat)GL_NEAREST);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, (GLfloat)GL_NEAREST);

   // sixth texture  - reuse third image
   glBindTexture(GL_TEXTURE_2D, state->tex[5]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, IMAGE_SIZE, IMAGE_SIZE, 0,
                GL_RGB, GL_UNSIGNED_BYTE, state->tex_buf3);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, (GLfloat)GL_NEAREST);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, (GLfloat)GL_NEAREST);

   // setup overall texture environment
   glTexCoordPointer(2, GL_FLOAT, 0, texCoords);
   glEnableClientState(GL_TEXTURE_COORD_ARRAY);
}

/***********************************************************
 * Name: load_tex_images
 *
 * Arguments:
 *       void
 *
 * Description: Loads three raw images to use as textures on faces
 *
 * Returns: void
 *
 ***********************************************************/
static void load_tex_images(CUBE_STATE_T *state)
{
   FILE *tex_file1 = NULL, *tex_file2=NULL, *tex_file3 = NULL;
   int bytes_read, image_sz = IMAGE_SIZE*IMAGE_SIZE*3;

   state->tex_buf1 = malloc(image_sz);
   state->tex_buf2 = malloc(image_sz);
   state->tex_buf3 = malloc(image_sz);

   tex_file1 = fopen(PATH "Lucca_128_128.raw", "rb");
   if (tex_file1 && state->tex_buf1)
   {
      bytes_read=fread(state->tex_buf1, 1, image_sz, tex_file1);
      assert(bytes_read == image_sz);  // some problem with file?
      fclose(tex_file1);
   }

   tex_file2 = fopen(PATH "Djenne_128_128.raw", "rb");
   if (tex_file2 && state->tex_buf2)
   {
      bytes_read=fread(state->tex_buf2, 1, image_sz, tex_file2);
      assert(bytes_read == image_sz);  // some problem with file?
      fclose(tex_file2);
   }

   tex_file3 = fopen(PATH "Gaudi_128_128.raw", "rb");
   if (tex_file3 && state->tex_buf3)
   {
      bytes_read=fread(state->tex_buf3, 1, image_sz, tex_file3);
      assert(bytes_read == image_sz);  // some problem with file?
      fclose(tex_file3);
   }
}

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

static void exit_func(void)
// Function to be passed to atexit().
{
   // clear screen
   glClear( GL_COLOR_BUFFER_BIT );
   eglSwapBuffers(state->display, state->surface);

   // Release OpenGL resources
   eglMakeCurrent( state->display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT );
   eglDestroySurface( state->display, state->surface );
   eglDestroyContext( state->display, state->context );
   eglTerminate( state->display );

   // release texture buffers
   free(state->tex_buf1);
   free(state->tex_buf2);
   free(state->tex_buf3);

   printf("\ncube closed\n");
} // exit_func()

//==============================================================================

int main ()
{
   bcm_host_init();

   // Clear application state
   memset( state, 0, sizeof( *state ) );

   // Start OGLES
   init_ogl(state);

   // Setup the model world
   init_model_proj(state);

   // initialise the OGLES texture(s)
   init_textures(state);

   while (!terminate)
   {
      //usleep(5*1000);
      update_model(state);
      redraw_scene(state);
   }
   exit_func();
  return 0;
}