Jump to content
  • Advertisement
Sign in to follow this  
Shirakana2

Transform feedback

This topic is 2809 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

Hi !
I'm trying to implement an algorithm using Transform Feedback feature but I'm having trouble reading the data back to process them. I may do something wrong but I really can't figure out what. Please help !

Here is the initialization stuff:

--------------------
// Data structure to store Eye space position and Screen Space position
struct ES_AND_SS {
float x,y,z;
int u,v;
};

// Buffer to store data
ES_AND_SS* tabData;

// Varying names to be recorded from vertex shader output
static const char* varyingNames[] = {
"ESPosition",
"ssCoord"
};

// Initializing data buffer
glTransformFeedbackVaryings(myProgramID,2,varyingNames,GL_INTERLEAVED_ATTRIBS);

glGenBuffers(1,&bufferID);
size = 1000;

// Allocate space
tabData = new ES_AND_SS[size];
glBufferData(GL_TRANSFORM_FEEDBACK_BUFFER,size*sizeof(ES_AND_SS), NULL, GL_DYNAMIC_READ);

----------------

// When rendering:
myProgram->activate();
glBindBuffer(GL_TRANSFORM_FEEDBACK_BUFFER,bufferID);
glBeginTransformFeedback(GL_POINTS);

//... draw some vertices ...

myProgram->deactivate();
glEndTransformFeedback();

// Reading back data
glGetBufferSubData(GL_TRANSFORM_FEEDBACK_BUFFER, 0, size*sizeof(ES_AND_SS), tabData);

// unbind
glBindBuffer(GL_TRANSFORM_FEEDBACK_BUFFER,0);

-----------------
But when parsing my data buffer I just get crappy values.
What the hell am I doing wrong ?

Thanks for your answers

Share this post


Link to post
Share on other sites
Advertisement
Ok I've got one of the answer: DO NOT FORGET TO BIND YOUR BUFFER BEFORE CALLING glBufferData(..)

So now the glGetBufferSubData(..) is ok but I still read 0.0 in all my data :(

Share this post


Link to post
Share on other sites
After many tests I realized that INTERLEAVED mode of transform feedback simply doesn't work, whereas SEPARATE mode works very well (driver bug ?). So much time lost for this :(

So don't use GL_INTERLEAVED_ATTRIBS but GL_SEPARATE_ATTRIBS instead !!

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!