Sign in to follow this  
GloW_on_dub

OpenGL Reading from Texture2D filled by the FBO

Recommended Posts

GloW_on_dub    102
Hello. I'm currently impementing Dpeht peeling algorithm. So i need to 1.render a scene. 2.Copy the depth buffer into a texture 3.give the texture to my fragment shader 4.rerender with activate depth test in my fragment shader I currently try to copy the depth buffer into a texture, i think it's working but i need to display the depth values to check it. in the same way, i have a color texture filled so by the fbo, before i display just the color_attachement0EXT with printf to check each pixel but now i'm trying to display the texture i suposed to be right atttached with the fbo. For this two case, i have incorrect results (seems like unallocated memory) here is my code (i dont know how to format it, please modo help) :
GLuint fbo;
GLuint img;	
GLuint txDepth;


int onlyFirst(const mesh_t *mesh,
face_t** boundary_face,
index_t* num_boundary_faces,real3 * origin, real3 * dir,real3 * up,unsigned int W,unsigned int H,float fovy,float near,float far)

{

    
    GLuint program;     /* notre program */

    int use_shaders = 0;/* booleen indiquant si l'on utilise les shaders */

    

    /* initialisation de la SDL en mode OpenGL */

    if(SDL_Init(SDL_INIT_VIDEO) < 0)

        exit(EXIT_FAILURE);

    if(SDL_SetVideoMode(W, H, 32, SDL_OPENGL) == NULL)

        ShutDown(EXIT_FAILURE);

    

    /* nom de la fenetre */

    SDL_WM_SetCaption("GLSL Shaders", NULL);



    /* initialisation de glew */

    glewInit();


     

  // Now setup a texture to render to

	glGenTextures(1, &img);

	glBindTexture(GL_TEXTURE_2D, img);

		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8,  W, H, 0, GL_RGBA,          GL_UNSIGNED_BYTE, NULL);

		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);

		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_NEAREST);

		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_NEAREST);




//setup a depth texture
	glGenTextures(1, &txDepth);
	glBindTexture(GL_TEXTURE_2D, txDepth);
		

	
 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 glTexParameteri(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_INTENSITY);
 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_R_TO_TEXTURE);
 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL);
 //NULL means reserve texture memory, but texels are undefined
 glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32, W, H, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);

glBindTexture( GL_TEXTURE_2D, 0 );


// Setup our FBO

	glGenFramebuffersEXT(1, &fbo);

	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);


// And attach it to the FBO so we can render to it

	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, img, 0);
// And attach it to the FBO so we can render to it
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_TEXTURE_2D, txDepth, 0);

	

GLubyte * data;
data = (GLubyte*)malloc(W*H*4*sizeof(GLubyte));
GLfloat * depthData;
depthData = (GLfloat*)malloc(W*H*sizeof(GLfloat));
int i;



GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);

	if(status != GL_FRAMEBUFFER_COMPLETE_EXT)
{
printf("status :%u",status);

		exit(1);
}

	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

// First we bind the FBO so we can render to it

	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);

// Save the view port and set it to the size of the texture

 glEnable(GL_DEPTH_TEST);
glClearColor(255,255,255,255);



// S e t t h e p r o j e c t i o n t r a n s f o r m
glMatrixMode (GL_PROJECTION ) ;
glLoadIdentity ( ) ;
gluPerspective( fovy, (GLfloat)W/(GLfloat)H,near, far ); 


// S e t t h e camera o r i e n t a t i o n :
glMatrixMode (GL_MODELVIEW) ;
glLoadIdentity();
gluLookAt(origin->x, origin->y, origin->z,origin->x+dir->x,origin->y+dir->y,origin->z+dir->z, up->x, up->y, up->z);

 glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

       


draw(mesh,
boundary_face,
num_boundary_faces);



   

//Recuperation des donées de la texture de rendu

/*glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
    glReadPixels(0, 0, W, H,GL_RGBA,GL_UNSIGNED_BYTE,data);   */
// the way i can get the pixel color before.

glBindTexture(GL_TEXTURE_2D, img);
   glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA8, GL_UNSIGNED_BYTE, data);
//the way not working
printf("BEGIN_RESULTS ONLY_FIRST \n"); 
    for (i=0; i<(W*H*4); i=i+4) 
{
	printf("row =%u :",(i/4)/W);
	printf("column =%u :",(i/4)%W);
	printf("%u\n",indexConvert(data[i],data[i+1],data[i+2],data[i+3]));
}

glBindTexture(GL_TEXTURE_2D, txDepth);
   glGetTexImage(GL_TEXTURE_2D, 0, GL_RED, GL_FLOAT, depthData); 
printf("BEGIN_RESULTS ONLY_FIRST \n"); 
    for (i=0; i<(W*H*4); i=i+4) 
{
	printf("row =%u :",(i/4)/W);
	printf("column =%u :",(i/4)%W);
	printf("%f\n",depthData[i]);
}


printf("END_RESULTS ONLY_FIRST \n"); 



 
free(data);
free(depthData);
 glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	glDeleteFramebuffersEXT(1, &fbo);

	glDeleteTextures(1,&img);
	glDeleteTextures(1,&txDepth);

    

    return EXIT_SUCCESS;

}


void colorConvert(unsigned int index)
{
GLubyte * pIdx = (GLubyte*)&index;
glColor4ub(pIdx[0],pIdx[1],0,0);

}

int indexConvert(GLushort r,GLushort g, GLubyte b, GLubyte a)
{
unsigned int idx;
GLubyte * pIdx=(GLubyte*)&idx;
pIdx[0]=r;
pIdx[1]=g;
pIdx[2]=b;
pIdx[3]=a;

return idx;
}

void draw(
const mesh_t *mesh,
face_t** boundary_face,
index_t* num_boundary_faces)
{
glMatrixMode (GL_MODELVIEW) ;
     glBegin(GL_QUADS);
glPushMatrix();

            colorConvert(1001);
glVertex3f(-10, 0, 2 );
glVertex3f( 10,0, 2);
glVertex3f( 10,-10,2); 
glVertex3f( -10,-10,2); 

glPopMatrix();
glEnd();
}



i know there is some strange things in my code i havent explain, but there is no incidence on my current problem.

Share this post


Link to post
Share on other sites

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 povilaslt2
      Hello. I'm Programmer who is in search of 2D game project who preferably uses OpenGL and C++. You can see my projects in GitHub. Project genre doesn't matter (except MMO's :D).
    • By ZeldaFan555
      Hello, My name is Matt. I am a programmer. I mostly use Java, but can use C++ and various other languages. I'm looking for someone to partner up with for random projects, preferably using OpenGL, though I'd be open to just about anything. If you're interested you can contact me on Skype or on here, thank you!
      Skype: Mangodoor408
    • By tyhender
      Hello, my name is Mark. I'm hobby programmer. 
      So recently,I thought that it's good idea to find people to create a full 3D engine. I'm looking for people experienced in scripting 3D shaders and implementing physics into engine(game)(we are going to use the React physics engine). 
      And,ye,no money =D I'm just looking for hobbyists that will be proud of their work. If engine(or game) will have financial succes,well,then maybe =D
      Sorry for late replies.
      I mostly give more information when people PM me,but this post is REALLY short,even for me =D
      So here's few more points:
      Engine will use openGL and SDL for graphics. It will use React3D physics library for physics simulation. Engine(most probably,atleast for the first part) won't have graphical fron-end,it will be a framework . I think final engine should be enough to set up an FPS in a couple of minutes. A bit about my self:
      I've been programming for 7 years total. I learned very slowly it as "secondary interesting thing" for like 3 years, but then began to script more seriously.  My primary language is C++,which we are going to use for the engine. Yes,I did 3D graphics with physics simulation before. No, my portfolio isn't very impressive. I'm working on that No,I wasn't employed officially. If anybody need to know more PM me. 
       
    • By Zaphyk
      I am developing my engine using the OpenGL 3.3 compatibility profile. It runs as expected on my NVIDIA card and on my Intel Card however when I tried it on an AMD setup it ran 3 times worse than on the other setups. Could this be a AMD driver thing or is this probably a problem with my OGL code? Could a different code standard create such bad performance?
    • By Kjell Andersson
      I'm trying to get some legacy OpenGL code to run with a shader pipeline,
      The legacy code uses glVertexPointer(), glColorPointer(), glNormalPointer() and glTexCoordPointer() to supply the vertex information.
      I know that it should be using setVertexAttribPointer() etc to clearly define the layout but that is not an option right now since the legacy code can't be modified to that extent.
      I've got a version 330 vertex shader to somewhat work:
      #version 330 uniform mat4 osg_ModelViewProjectionMatrix; uniform mat4 osg_ModelViewMatrix; layout(location = 0) in vec4 Vertex; layout(location = 2) in vec4 Normal; // Velocity layout(location = 3) in vec3 TexCoord; // TODO: is this the right layout location? out VertexData { vec4 color; vec3 velocity; float size; } VertexOut; void main(void) { vec4 p0 = Vertex; vec4 p1 = Vertex + vec4(Normal.x, Normal.y, Normal.z, 0.0f); vec3 velocity = (osg_ModelViewProjectionMatrix * p1 - osg_ModelViewProjectionMatrix * p0).xyz; VertexOut.velocity = velocity; VertexOut.size = TexCoord.y; gl_Position = osg_ModelViewMatrix * Vertex; } What works is the Vertex and Normal information that the legacy C++ OpenGL code seem to provide in layout location 0 and 2. This is fine.
      What I'm not getting to work is the TexCoord information that is supplied by a glTexCoordPointer() call in C++.
      Question:
      What layout location is the old standard pipeline using for glTexCoordPointer()? Or is this undefined?
       
      Side note: I'm trying to get an OpenSceneGraph 3.4.0 particle system to use custom vertex, geometry and fragment shaders for rendering the particles.
  • Popular Now