Sign in to follow this  

OpenGL Texture wont show on quad.

This topic is 1797 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I made this thread in For Beginners, but noone there was able to help.

 

 

I was having trouble loading the image, but have since fixed that. Now I cant seem to get the image to actually show on the screen. Instead its just the blue rectangle I have drawn with no texture on it.

 

#include "SDL.h"
#include "SDL_image.h"
#include "SDL_opengl.h"
#include <math.h>
#include <stdio.h>

int loadImage();
void drawImage();

extern SDL_Event event;

GLuint texture = NULL;
GLenum texture_format=NULL;
GLint nofcolors;

bool initGL()
{
    //Initialize Projection Matrix
    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();

    //Initialize Modelview Matrix
    glOrtho(0, 1200, 700, 0, -1, 1);
	glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();

    //Initialize clear color
   glClearColor(1.0,.4,0.0,0.0);
   glEnable( GL_TEXTURE_2D);
    //Check for error
    GLenum error = glGetError();
    if( error != GL_NO_ERROR )
    {
        printf( "Error initializing OpenGL! %s\n", gluErrorString( error ) );
        return false;
    }

    return true;
}

bool init()
{
    //Initialize SDL
    if( SDL_Init( SDL_INIT_EVERYTHING ) < 0 )
    {
        return false;
    }

	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1);

    //Create Window
    if( SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_OPENGL ) == NULL )
    {
        return false;
    }

    //Enable unicode
    SDL_EnableUNICODE( SDL_TRUE );

	


    //Initialize OpenGL
    if( initGL() == false )
    {
        return false;
    }

    //Set caption
    SDL_WM_SetCaption( "Project Birth Game Window. Guns&Player.", NULL );

    return true;
}




int main( int argc, char *argv[] )
{
    //Quit flag
    bool quit = false;

    //Initialize
    if( init() == false )
    {
        return 1;
    }

    //The frame rate regulator
    Timer fps;
	fps.start();
	loadImage(); 


	int x = 0, y = 0;
	//Wait for user exit
	while( quit == false )
	{
        //Start the frame timer
        
		
        //While there are events to handle
		while( SDL_PollEvent( &event ) )
		{
			if( event.type == SDL_QUIT )
			{
                quit = true;
            }
			
			else if( event.type == SDL_KEYDOWN )
            {
                //Handle keypress with current mouse position
                
				SDL_GetMouseState( &x, &y );
                
			}
		}

	
		drawImage(); 

       
        update(); 
		
		SDL_GL_SwapBuffers();
		
        //Cap the frame rate
        if( fps.get_ticks() < 1000 / FRAMES_PER_SECOND )
        {
            SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - fps.get_ticks() );
        }
	}

	//Clean up
	clean_up();

	return 0;
}




int loadImage()
{


	SDL_Surface* surface;
	
	
	if((surface = IMG_Load("Avatar Basic Character Model.jpg")))
	{
	
		

	//get number of channels in the SDL surface
	nofcolors = surface -> format -> BytesPerPixel;
	
   //contains an alpha channel
	if(nofcolors == 4)
	{
		if ( surface -> format -> Rmask == 0x000000ff)
			texture_format = GL_RGBA;
		else
			texture_format = GL_BGRA;
	}
	else if ( nofcolors == 3) //no alpha channel
	{
		if(surface ->format->Rmask==0x000000ff)
			texture_format=GL_RGB;
		else
			texture_format=GL_BGR;
	}

	//Have Opengl generate a texture object handle for us
	glGenTextures(1, &texture);

	//Bind the texture object
	glBindTexture( GL_TEXTURE_2D, texture);

	//Set the texture's stretching properties
	glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glPixelStorei(GL_UNPACK_ALIGNMENT,1);

	
	glTexImage2D( GL_TEXTURE_2D, 0, nofcolors, surface -> w, surface ->h, 0, texture_format, GL_UNSIGNED_BYTE, surface -> pixels );
	
	}
	else //could not load image
		return -1;


if (surface)
{
	SDL_FreeSurface(surface);
}

return 1; 

}


void drawImage()
{

	//Clear the screen before drawing 
	glClear( GL_COLOR_BUFFER_BIT);

	//Bind the texture to which subsequent calls refer to
	glBindTexture( GL_TEXTURE_2D, texture);

	glPushMatrix();
	glTranslatef(300,300,0.0f);
	glBegin(GL_QUADS);
	//Set color
	glColor4f(0.0,0.0,1.0,0.0);

	
	glTexCoord2i(1,1);
	glVertex2f(150.0,0);//bottom right
	
	glTexCoord2i(0,1);
	glVertex2f(150.0,-50);//top right
	
	glTexCoord2i(0,0);
	glVertex2f(0.0,-50);//top left
	
	glTexCoord2i(1,0);
	glVertex2f(0.0,0);//bottom left
    

	glEnd();
	
	glPopMatrix();

	
}

 

At first I was having issues with loading the image, but thats no longer an issue. Any idea on why the image wont show on the quad? Perhaps an issue with binding?

 

Share this post


Link to post
Share on other sites

The code works as it is for me. Check for OpenGL errors in your code.

The image shows on screen for you? How can that be?

Share this post


Link to post
Share on other sites

Probably because there's nothing wrong with the code itself, but the environment in which you run it. For example, you may be trying to load a non-power of two texture in an environment that can only handle power of two textures. As I said, check for errors.

Share this post


Link to post
Share on other sites

Also this is not related to your question but you may find it helpful anyway to know that when using C++ you should use the C++ headers instead of the C headers.

 

#include <math.h> #include <cmath>

#include <stdio.h> #include <cstdio>

 

 

L. Spiro

Share this post


Link to post
Share on other sites

Also this is not related to your question but you may find it helpful anyway to know that when using C++ you should use the C++ headers instead of the C headers.
 
#include <math.h> #include <cmath>
#include <stdio.h> #include <cstdio>
 
 
L. Spiro

while fair enough, it is not made clear here that the code in question is C++, rather than C99 (clarification: C code looking like that given will generally be accepted by GCC, which implements C99 support, well, along with much of C11). (this comment is N/A if in-fact the OP is using C++). Edited by cr88192

Share this post


Link to post
Share on other sites
Something else to mention to the original topic-poster: Fixed your random-style indentations. You have random indentations all over the place. Why? It is just shooting yourself in the foot.
There are guidelines for indenting that, time-tested and mother-approved, will help both you and anyone else read your code. You should adhere to indentation guidelines strictly.


L. Spiro

Share this post


Link to post
Share on other sites

This topic is 1797 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Similar Content

    • By xhcao
      Does sync be needed to read texture content after access texture image in compute shader?
      My simple code is as below,
      glUseProgram(program.get());
      glBindImageTexture(0, texture[0], 0, GL_FALSE, 3, GL_READ_ONLY, GL_R32UI);
      glBindImageTexture(1, texture[1], 0, GL_FALSE, 4, GL_WRITE_ONLY, GL_R32UI);
      glDispatchCompute(1, 1, 1);
      // Does sync be needed here?
      glUseProgram(0);
      glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffer);
      glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                     GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, texture[1], 0);
      glReadPixels(0, 0, kWidth, kHeight, GL_RED_INTEGER, GL_UNSIGNED_INT, outputValues);
       
      Compute shader is very simple, imageLoad content from texture[0], and imageStore content to texture[1]. Does need to sync after dispatchCompute?
    • By Jonathan2006
      My question: is it possible to transform multiple angular velocities so that they can be reinserted as one? My research is below:
      // This works quat quaternion1 = GEQuaternionFromAngleRadians(angleRadiansVector1); quat quaternion2 = GEMultiplyQuaternions(quaternion1, GEQuaternionFromAngleRadians(angleRadiansVector2)); quat quaternion3 = GEMultiplyQuaternions(quaternion2, GEQuaternionFromAngleRadians(angleRadiansVector3)); glMultMatrixf(GEMat4FromQuaternion(quaternion3).array); // The first two work fine but not the third. Why? quat quaternion1 = GEQuaternionFromAngleRadians(angleRadiansVector1); vec3 vector1 = GETransformQuaternionAndVector(quaternion1, angularVelocity1); quat quaternion2 = GEQuaternionFromAngleRadians(angleRadiansVector2); vec3 vector2 = GETransformQuaternionAndVector(quaternion2, angularVelocity2); // This doesn't work //quat quaternion3 = GEQuaternionFromAngleRadians(angleRadiansVector3); //vec3 vector3 = GETransformQuaternionAndVector(quaternion3, angularVelocity3); vec3 angleVelocity = GEAddVectors(vector1, vector2); // Does not work: vec3 angleVelocity = GEAddVectors(vector1, GEAddVectors(vector2, vector3)); static vec3 angleRadiansVector; vec3 angularAcceleration = GESetVector(0.0, 0.0, 0.0); // Sending it through one angular velocity later in my motion engine angleVelocity = GEAddVectors(angleVelocity, GEMultiplyVectorAndScalar(angularAcceleration, timeStep)); angleRadiansVector = GEAddVectors(angleRadiansVector, GEMultiplyVectorAndScalar(angleVelocity, timeStep)); glMultMatrixf(GEMat4FromEulerAngle(angleRadiansVector).array); Also how do I combine multiple angularAcceleration variables? Is there an easier way to transform the angular values?
    • By dpadam450
      I have this code below in both my vertex and fragment shader, however when I request glGetUniformLocation("Lights[0].diffuse") or "Lights[0].attenuation", it returns -1. It will only give me a valid uniform location if I actually use the diffuse/attenuation variables in the VERTEX shader. Because I use position in the vertex shader, it always returns a valid uniform location. I've read that I can share uniforms across both vertex and fragment, but I'm confused what this is even compiling to if this is the case.
       
      #define NUM_LIGHTS 2
      struct Light
      {
          vec3 position;
          vec3 diffuse;
          float attenuation;
      };
      uniform Light Lights[NUM_LIGHTS];
       
       
    • By pr033r
      Hello,
      I have a Bachelor project on topic "Implenet 3D Boid's algorithm in OpenGL". All OpenGL issues works fine for me, all rendering etc. But when I started implement the boid's algorithm it was getting worse and worse. I read article (http://natureofcode.com/book/chapter-6-autonomous-agents/) inspirate from another code (here: https://github.com/jyanar/Boids/tree/master/src) but it still doesn't work like in tutorials and videos. For example the main problem: when I apply Cohesion (one of three main laws of boids) it makes some "cycling knot". Second, when some flock touch to another it scary change the coordination or respawn in origin (x: 0, y:0. z:0). Just some streng things. 
      I followed many tutorials, change a try everything but it isn't so smooth, without lags like in another videos. I really need your help. 
      My code (optimalizing branch): https://github.com/pr033r/BachelorProject/tree/Optimalizing
      Exe file (if you want to look) and models folder (for those who will download the sources):
      http://leteckaposta.cz/367190436
      Thanks for any help...

    • By Andrija
      I am currently trying to implement shadow mapping into my project , but although i can render my depth map to the screen and it looks okay , when i sample it with shadowCoords there is no shadow.
      Here is my light space matrix calculation
      mat4x4 lightViewMatrix; vec3 sun_pos = {SUN_OFFSET * the_sun->direction[0], SUN_OFFSET * the_sun->direction[1], SUN_OFFSET * the_sun->direction[2]}; mat4x4_look_at(lightViewMatrix,sun_pos,player->pos,up); mat4x4_mul(lightSpaceMatrix,lightProjMatrix,lightViewMatrix); I will tweak the values for the size and frustum of the shadow map, but for now i just want to draw shadows around the player position
      the_sun->direction is a normalized vector so i multiply it by a constant to get the position.
      player->pos is the camera position in world space
      the light projection matrix is calculated like this:
      mat4x4_ortho(lightProjMatrix,-SHADOW_FAR,SHADOW_FAR,-SHADOW_FAR,SHADOW_FAR,NEAR,SHADOW_FAR); Shadow vertex shader:
      uniform mat4 light_space_matrix; void main() { gl_Position = light_space_matrix * transfMatrix * vec4(position, 1.0f); } Shadow fragment shader:
      out float fragDepth; void main() { fragDepth = gl_FragCoord.z; } I am using deferred rendering so i have all my world positions in the g_positions buffer
      My shadow calculation in the deferred fragment shader:
      float get_shadow_fac(vec4 light_space_pos) { vec3 shadow_coords = light_space_pos.xyz / light_space_pos.w; shadow_coords = shadow_coords * 0.5 + 0.5; float closest_depth = texture(shadow_map, shadow_coords.xy).r; float current_depth = shadow_coords.z; float shadow_fac = 1.0; if(closest_depth < current_depth) shadow_fac = 0.5; return shadow_fac; } I call the function like this:
      get_shadow_fac(light_space_matrix * vec4(position,1.0)); Where position is the value i got from sampling the g_position buffer
      Here is my depth texture (i know it will produce low quality shadows but i just want to get it working for now):
      sorry because of the compression , the black smudges are trees ... https://i.stack.imgur.com/T43aK.jpg
      EDIT: Depth texture attachment:
      glTexImage2D(GL_TEXTURE_2D, 0,GL_DEPTH_COMPONENT24,fbo->width,fbo->height,0,GL_DEPTH_COMPONENT,GL_FLOAT,NULL); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, fbo->depthTexture, 0);
  • Popular Now