DEPTH_STENCIL_SLOT :: 42;

// The slots used by the render pass render targets
// Slots 10-17 are reserved for the passes
Render_Target_Shader_Slots :: enum {
    SLOT0 :: 10;
    SLOT1 :: 11;
    SLOT2 :: 12;
    SLOT3 :: 13;
    SLOT4 :: 14;
    SLOT5 :: 15;
    SLOT6 :: 16;
    SLOT7 :: 17;
}

Render_Target_Info :: struct {
    format: Format;
    width: u32;
    height: u32;

    clear_color: Color;
}

Depth_Stencil_Info :: struct {
    enabled: bool;
    format: Format;
    width: u32;
    height: u32;
}

Render_Pass_Input_Info :: struct {
    pass_handle: Render_Pass_Handle;
    rt_index: u32; // the index into the render pass
}

Render_Pass :: struct {
    name: string;

    inputs: [..] Render_Pass_Input_Info;

    uses_backbuffer: bool;
    render_targets: [..] Render_Target_Handle;
    clear_colors: [..] Color;
    depth_stencil: Depth_Stencil_Buffer_Handle;
    has_depth_stencil: bool;

    width: u32;
    height: u32;

    callback: (pass: Render_Pass);
}

create_render_pass :: (graph: *Render_Graph, name: string, callback: (Render_Pass), render_target_infos: [] Render_Target_Info = .[], depth_stencil_info : Depth_Stencil_Info = .{}, uses_backbuffer: bool = false) -> Render_Pass_Handle {
    render_pass : Render_Pass;
    render_pass.name = copy_string(name);
    render_pass.uses_backbuffer = uses_backbuffer;
    render_pass.callback = callback;

    if depth_stencil_info.enabled {
        render_pass.has_depth_stencil = true;
        render_pass.depth_stencil = create_depth_stencil_buffer(depth_stencil_info.width, depth_stencil_info.height, 0);
        render_pass.width = depth_stencil_info.width;
        render_pass.height = depth_stencil_info.height;
    }

    array_reserve(*render_pass.render_targets, render_target_infos.count);
    array_reserve(*render_pass.clear_colors, render_target_infos.count);

    for render_target_infos {
        array_add(*render_pass.render_targets, create_render_target(it.width, it.height, it.format));
        array_add(*render_pass.clear_colors, it.clear_color);
        render_pass.width = it.width;
        render_pass.height = it.height;
    }

    return parray_add(*graph.render_passes, render_pass);
}

add_render_pass_input :: (graph: *Render_Graph, to_pass: Render_Pass_Handle, from_pass: Render_Pass_Handle, rt_index: u32) {
    info : Render_Pass_Input_Info;
    info.pass_handle = from_pass;
    info.rt_index = rt_index;

    pass := parray_get(*graph.render_passes, to_pass);
    array_add(*pass.inputs, info);
}

get_texture_from_pass :: (name: string) -> Texture_Handle {
    for engine.renderer.render_graph.render_passes {
        if it.name == name {
            rt := parray_get(engine.renderer.render_targets, it.render_targets[0]);
            return rt.texture;
        }
    }

    return xx 0;
}