While debugging an issue with the dx11 backend, I noticed that 4coder only clipped rectangles that are outside the screen vertically. Another potential issue (it might be the intended behavior) causes some things to not work with line wrapping, which means that we could have very long horizontal lines, causing a lot of vertices being sent through the render pipeline that will just be clipped after the vertex shader. This causes higher than necessary GPU memory usage, and low performance for things that aren't rendered in the end.
An example of problematic is:
```c
u8 data[ ] = {0,0,0,0,...,0}; // With a lot of zero, and no space between them.
```
This fix just checks that at least one vertex of each rectangle we try to draw is in the screen. It would be better to use the current clip rect, but it's not available at that point in the pipeline. If we want we can modify the API a little to pass it down, as a parameter to those functions.
Using RenderDoc, I saw the vertex count going from over 500K to 13K with this change, and the performance were from 57ms to 25ms. So perfs are not great (but still an improvement), but testing the bounds of 500K vertices is not free. Fixing the line wrapping issue would probably help getting back to reasonable frame rate.
code/platform_win32/win32_4ed.cpp:
- Modification to be able to choose between OpenGL and DirectX. You choose between the two by defining WIN32_DIRECTX macro. If you don't define it it uses OpenGL.
- Note that win32_gl_create_window and other part of the file that depend on OpenGL or DirectX have been moved to win32_opengl.cpp and win32_directx.cpp.
- Fixed os_popup_error using the title as the message and the message as the title.
code/platform_win32/win32_opengl.cpp: Contains previous code that was in win32_4ed.cpp.
code/platform_win32/win32_directx.cpp: Code for creating a DirectX window and context.
code/platform_win32/4ed_directx_render.cpp: Imlementation of the 4coder renderer using DirectX.
To see the issues, you can set the font atlas size to 128 * 128 by changing line 325 "ft__bad_rect_pack_init(&pack, V2i32(1024, 1024));" to "ft__bad_rect_pack_init(&pack, V2i32(128, 128));".
The first issue was that the max_dim.y parameter was not respected. The dimension produced would always grow on Y to accommodate for more characters. And so the whole texture array thing was never use.
A second issue was that when a character didn't fit on the x axis, we created a new line, but never check that the new line fitted in the current texture slice.
A third issue was that when we ended a line because a character didn't fit vertically, we grew the line with a line height equal to the height of the character that didn't fit.
Simon Anciaux
Peter Slattery