Opengl 4.3 wall collision driver#
Opengl 4.3 wall collision full#

Opengl 4.3 wall collision full#

This is a bit off-topic, but you simply need to call glPixelStorei(GL_UNPACK_ALIGNMENT, 1).ДЄnd finally, you can call glReadPixels ! Here is the full code : You also need to configure how glReadPixels will behave with respect to memory alignment. The difference with glFlush() is that glFlush() just sends the commands glFinish() waits for these commands to be executed. Then, you need to call glFinish(), which will wait until everything is really drawn. It WILL be drawn a few milliseconds later). This is typically not done automatically, because commands are sent in batches, and not immediately (this means that when you call glDrawElements(), nothing is actually draw.

Opengl 4.3 wall collision driver#

This will tell the OpenGL driver to send all the pending commands (including your latest glDrawXX) to the GPU. But for this function to work, a few more calls are needed.ДЇirst, you need to call glFlush(). When you have drawn all meshes (probably with a for() loop), you need to call glReadPixels(), which will retrieve the rasterized pixels on the CPU. You can now draw the meshes as usual ( glBindBuffer, glVertexAttribPointer, glDrawElements) and youвЂ™ll get the weird picture above. OpenGL expects colors to be in, so divide by 255. In this simple example, the picking is done each frame where the left mouse button is down : If you have a more complex hierarchy, youвЂ™ll probably need to add the ID to your Mesh class, and maintain some sort of std::map to associate the ID with the desired object. In the accompanying source code, 100 objects are created and stored in a std::vector, so the ID is just the index of the object in the vector. This color doesnвЂ™t have to have a meaning this technique is just a hack anyway. The easiest way to do this is to give each object an identifying integer, and convert it to a color. Implementation Giving an ID to every objectД®ach object of the scene will need a unique color. Of course, you donвЂ™t want to see the image with all these weird colors, so you also have to clear the screen and re-draw as usual.

In this screenshot, each monkey has a slightly different color, which make is possible to uniquely identify them. Then, you retrieve the colour of the pixel under the mouse cursor and convert this color back to the original identifier. The idea behind this technique is to render the scene as usual, but instead of using a nice shading, you render each mesh with a specific and unique color. Source code for this tutorial is available in misc05_picking/misc05_picking_slow_easy.cpp, which is a quite meaningful name. However, if you have some kind of simulation and you donвЂ™t really care about picking performance, this might the perfect option. By all means, avoid using this in a game, since it might introduce noticeable framerate drops. This technique is not really recommended, but itвЂ™s an easy and fast way to add simple picking.