feature request: custom vertex format

[nowakf]

I figured this would solve #256 in a somewhat elegant way, and from looking at the stuff in quad_gl.rs and in graphics.rs (in miniquad) it seems that it should be straightforward to do something like make Quadgl generic over vertex type (since Buffer is generic over vertex type anyway).

It feels to me that normals are quite important for 3d objects, so if it isn't so straightforward, it's still probably a nice thing to have :)

[Vrixyz]

From my understanding, you're suggesting modifications to the hardcoded type of Vertex stored within DrawCall:

macroquad/src/quad_gl.rs

Lines 20 to 21 in 305d472

	struct DrawCall {
	vertices: Vec<Vertex>,

in order to pass something different later to the buffer there:

macroquad/src/quad_gl.rs

Line 789 in 305d472

BufferSource::slice(dc.vertices()),

I think it's a good approach.

Alternatives

I´d like to discuss alternative or next steps (also helps with verifying my understanding):

Would another option be to allow to add more binding groups (so we´d be able to add our custom informations to it. The implementation might not be completely different, but might help with separating "custom data" from official macroquad information.

So feed different types within

macroquad/src/quad_gl.rs

Lines 749 to 753 in 305d472

	let bindings = Bindings {
	vertex_buffers: vec![vertex_buffer],
	index_buffer,
	images: vec![white_texture, white_texture],
	};

And rather than hardcoding 0, loop over their data to update them.

macroquad/src/quad_gl.rs

Lines 787 to 790 in 305d472

	ctx.buffer_update(
	bindings.vertex_buffers[0],
	BufferSource::slice(dc.vertices()),
	);