Do not use multiple rendering contexts with CUDA. It will cause some errors.

One problem I found when OpenGL buffer object used with CUDA in multiple rendering contexts.

When I have more than one rendering context, the opengl will return same buffer object ids for different buffer objects. The reason for returning same buffer object is nothing these are two rendering contexts.

See code below.

// Creating first buffer object with first rendering Context.

wglMakeCurrent( myRC1 );

glGenBuffers( 1, &myBuffer1 );// This id will be 1 in normal case.

// creating second buffer object with next rendering context.

wglMakeCurrent( myRC2 );

glGenBuffers( 1, &myBuffer2  );// This id also will be 1 in normal case.

// Then registering these buffers to CUDA.

cudaGLRegisterBufferObject( myBuffer1 ); // This will be success.

// Registering next buffer object.

cudaGLRegisterBufferObject( myBuffer2  ); // Here I’ll get Error .

The reason for this error is, cuda device depends on current thread. But openGL creates buffer objects based on rendering contexts. First register to cuda will succeeded, becouse its( 1) not registered yet. Then next register call will fail, becouse this buffer object id ( 1) is already registered for CUDA device.  I created two rendering contexts for this thread and hence two buffer objects will return same id.

Thats all friends.

glStarter.