load .png texture in hello_triangle example problem

[Balaji]

I am newbie to opengles.i tested the hello_triangle program and it works fine.but in this .raw texture were used.
i need to load tga or png texture but it shows error.

can u please help me to solve this.

[ffelagund]

Use an image loading library, like freeimage for example.

[Balaji]

hi i made some changes in hello_triangle but it shows error.here is my code.

cube_texture_and_coords.h

Code: Select all

// Spatial coordinates for the cube

static const GLbyte quadx[1*4*3] = {
   -6.626542, -7.047174, -0.000000,
    6.626542, -7.047174, -0.000000,
   -6.526089, 7.060534, -0.000000,
    6.526089, 7.060534, -0.000000,

};

/** Texture coordinates for the quad. */
static const GLfloat texCoords[1 * 4 * 2] = {
   0.f,  0.f,
   0.f,  1.f,
   1.f,  0.f,
   1.f,  1.f,
   
};

triangle.h

Code: Select all

// 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 1024

#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[1];
// 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;
 } 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;

static int i=0;

/***********************************************************
 * 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;//40
}

/***********************************************************
 * 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 = 9.5f;

   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);

   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
   //glEnable(GL_BLEND);
   
   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(0.f, 0.f, 0.f, 1.f ); // front face normal along z axis

   // draw first 4 vertices
   glDrawArrays( GL_TRIANGLE_STRIP, 0, 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(1, &state->tex[0]);

   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
   glEnable(GL_TEXTURE_2D);
   
   // setup first texture
   glBindTexture(GL_TEXTURE_2D, state->tex[0]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, IMAGE_SIZE, IMAGE_SIZE, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, state->tex_buf1);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, (GLfloat)GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, (GLfloat)GL_NEAREST);

   // setup overall texture environment
   glTexCoordPointer(1, 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;
   int bytes_read, image_sz = IMAGE_SIZE*IMAGE_SIZE*3;

   state->tex_buf1 = malloc(image_sz);
      
   tex_file1 = fopen(PATH "MyTexture.png", "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);
   }
              
}

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

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);
   
   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;
}

Error:

"hello_triangle.bin: triangle.c:398: load_tex_images: Assertion `bytes_read == image_sz' failed.
Aborted"

i am doing this work two weeks but still i didn,t get.Anybody can help me.

[OtherCrashOverride]

PNG files are containers for images. You have to process them to get the actual image data from them (usually with libpng). The actual image data is what opengl uses.

Here is an example of how to load a BMP file obtained by searching Google for "opengl texture loading tutorial":
http://www.opengl-tutorial.org/beginner ... ured-cube/

[OtherCrashOverride]

Here is an example of loading a PNG file obtained by searching Google for "opengl png texture loading tutorial":
http://stackoverflow.com/questions/1129 ... ibpng-only

[Balaji]

Now i can load a .tga texture but the background image was culling.how can i solve this.

[ffelagund]

Freeimage, use Freeimage: http://freeimage.sourceforge.net/
With that, you can load a png (or any other format) in less than 5 lines of code.

[techs1200]

Yeah use freeimage. Its really good!

[lobotony]

You can also give stb_image a try. It doesn't necessarily load all image file variants (e.g. no progressive jpeg support), but it's really small and easy to integrate. It's only a single C file: http://nothings.org/stb_image.c

[lobotony]

Balaji,

in response to your private message: if you're new to OpenGL and in a hurry, you should take a look at libs that help you with getting the basics out of the way. That still means you will need to get the hang of some OpenGL core concepts, but you won't necessarily need to mess with image loading libs, vertex buffers and draw call setups.
I've got some code here: https://github.com/lobotony/le2
Check it out on your Raspberry Pi, cd into le2/rpi, make, ln -s ../resources and run ./le2.out . Applications can be found in le2/apps. Choose which to run in rpi/main.cpp. The project is still in progress, but very usable. For basic 2D stuff, if you can wrap your head around mid-level C++ code and chain a few matrices, you will get your project done with this lib.

Best,
Tony