DX11 Graphics Backend

[matthewgeorgy]

Figured I'd put it in a separate branch to make tracking its progress easier.

Currently, only a few things have been implemented thus far, but the plumbing is laid out for many more things to be added in the future. To get an idea of how much is implemented, I can compile and run the 02_simple_triangle, 04_simple_texture, 07_instancing (with and without index buffers), and 19_uniform_buffer.

Implemented so far

Resource creation:

• gs_graphics_vertex_buffer_create(...)
• gs_graphics_index_buffer_create(...)
• gs_graphics_shader_create(...)
• gs_graphics_pipeline_create(...)
• gs_graphics_uniform_buffer_create(...)
• gs_graphics_uniform_create(...)
• gs_graphics_texture_create(...) (+ internal())

Resource Updates:

• __gs_graphics_update_buffer_internal(...)
• gs_graphics_uniform_buffer_update_request(...)

Command Buffer Ops:

• OP_BEGIN_RENDER_PASS
• OP_END_RENDER_PASS
• OP_SET_VIEWPORT
• OP_CLEAR
• OP_BIND_PIPELINE
• OP_APPLY_BINDINGS
• OP_DRAW
  Scrapped the command buffer + op code system in favour for ID3D11CommandLists.

Supported features:

• Vertex buffers
• Index buffers
• Uniform buffers
• Uniforms (DX11 SRV's)
• Textures
• Shaders
• Pipelines
• Instanced rendering

Command Buffer Funcs:

• gs_graphics_begin_render_pass(...)
• gs_graphics_end_render_pass(...)
• gs_graphics_clear(...)
• gs_graphics_set_viewport(...)
• gs_graphics_apply_bindings(...)
• gs_graphics_bind_pipeline(...)
• gs_graphics_draw(...)
• gs_graphics_submit_command_buffer(...)

The command buffer system works by first receiving the gs_graphics_pipeline object with the call to gs_graphics_bind_pipeline, binding shaders, and then caching it for later use. Then, using this cached pipeline, vertex buffer layouts are filled in under the OP_APPLY_BINDINGS instruction. Here, any appropriate vertex buffers are bound, and the ID3D11InputLayout is created here and also bound. The only purpose of the OP_DRAW instruction is to make the API draw call, using all of the data that was bound to the pipeline by the previous two instructions.
This is different from the OpenGL implementation, where the OP_DRAW instruction is also responsible for binding some necessary data. This is the design choice for now but, of course, it may change in the future.
NOTE: I have completely revamped the command buffer system by getting rid of it and using ID3D11CommandList and deferred contexts in order to support proper multithreaded rendering safety. I've also made use of CRITICAL_SECTION
objects to allow for safe multithreaded object creation.

Next Steps

• Proper thread safety with ID3D11CommandList + deferred context
• Support multiple uniforms (currently can only bind 1 uniform at a time)
• Changes to platform layer with GLFW so that the D3D11 backend can actually initialize properly (ie, getting an HWND, NO_CLIENT_API, etc)
• Framebuffers
• Compute shaders
• gunslinger immediate draw
• Support more uniform types(Buffers, etc)

My main testing philosophy is to get as many of the example apps running with this backend as possible. This also doubles as a simple way of tracking progress and figuring out what needs to be implemented next.