If we have no data to update/draw, we avoid update/draw. On `DrawBuffersDefault()` if no vertes data is available nothing is drawn but some globals: vertexData, projection, modelview, draws... are reseted.
There shouldn't be any problem if we don't touch those globals in case no vertex have been processed but, just in case, I warn about it.
When drawing LINES or TRIANGLES, vertex are accumulated in same buffer as QUADS and new draw calls are registered but QUADS drawing uses an index buffer for optimization, so, when adding LINES/TRIANGLES vertices we need to make sure next draw calls for QUADS keep aligned with indices buffer.
To get that we just add some alignment vertex at the end of the LINES/TRIANGLES draw calls, to make them multiple of 4 vertex.
When capturing framebuffer, if some element with transparency has been drawn, it retrieves that data... it could be a bit annoying in some situations because we could expect color compositing with background color... It depends on the situation and our needs... but most of the time we don't want that transparency on screenshots.
Specific textures generation code is quite redundant and not flexible for the user, I'm trying to figure out some easy way to allow raylib users to do the same without needing those functions (very specific and shader dependant). RenderTexture loading and Cubemap textures support must be improved.
Problem aligning provided vertex data to multiples of four, because main buffer is intended to bu used with indexed quads... but also shared with triangles and lines.
This commit implements a big update of rlgl module, intended to optimize some parts. This change could break some code bases... hopefully not, but it could.
The BIG changes to the module are:
- Replaced LINES-TRIANGLES-QUADS buffers by a single one, now all vertex data is accumulated on a single buffer and managed with registered draw calls. LINES-TRIANGLES-QUADS could be used the same way as before, rlgl will manage them carefully. That's a big improvement of the system.
- Support multi-buffering if required. Just define MAX_BATCH_BUFFERING desired size (currently set to 1 batch). Should be enough for most of the situations.
- Removed temporal accumulative buffers for matrix transformations, now transformations are directly applied to vertex when on rlVertex3f()
- Reviewed rlPushMatrix()/rlPopMatrix() to be consistent with OpenGL 1.1, probably I should remove that ancient behaviour but... well, it was not consistent and now it is.
- Minor tweaks: LoadText(), I broke it in last update... also multiple comments reviewed.
- TODO: MAX_BATCH_ELEMENTS checking should probably be reviewed... done some tests and it works but...
