[gpu.pass] graphics_state new members: index_buffer, draw_buffer and …

…triangle_count. note that only the latter is actually implemented

demo/tz/tz_triangle_demo.cpp

@@ -29,7 +29,8 @@ int main()
 		{
 			.clear_colour = {0.0f, 0.0f, 0.0f, 1.0f},
 			.colour_targets = colour_targets,
-			.depth_target = tz::gpu::window_resource
+			.depth_target = tz::gpu::window_resource,
+			.triangle_count = 1
 		},
 		.shader = graphics,
 	}));

include/tz/gpu/pass.hpp

@@ -94,10 +94,16 @@ namespace tz::gpu
 		std::span<const resource_handle> colour_targets = {};
 		/// Optional depth target. This will act as the depth image when performing depth testing/writes.
 		resource_handle depth_target = tz::nullhand;
+		/// Buffer containing indices used for every frame.
+		resource_handle index_buffer = tz::nullhand;
+		/// Buffer containing an initial count and draw commands for every frame.
+		resource_handle draw_buffer = tz::nullhand;
 		/// Describe which faces will be culled during rendering.
 		cull culling = cull::back;
 		/// Specifies extra optional behaviour for the pass.
 		graphics_flag flags = static_cast<graphics_flag>(0);
+		/// Number of triangles to draw in a frame. @note This is ignored if you are using a draw buffer.
+		std::size_t triangle_count = 0;
 	};
 
 	struct pass_compute_state

src/tz/gpu/rhi_vulkan.cpp

@@ -1013,6 +1013,14 @@ namespace tz::gpu
 		{
 			UNERR(tz::error_code::precondition_failure, "no shader program provided when creating pass. you must provide a valid shader program.");
 		}
+		if(info.graphics.index_buffer != tz::nullhand)
+		{
+			UNERR(tz::error_code::engine_bug, "support for index buffers is not yet implemented.");
+		}
+		if(info.graphics.draw_buffer != tz::nullhand)
+		{
+			UNERR(tz::error_code::engine_bug, "support for draw buffers is not yet implemented.");
+		}
 		std::size_t ret_id = passes.size();
 		auto& pass = passes.emplace_back();
 		std::size_t buffer_count = 0;
@@ -2386,7 +2394,7 @@ namespace tz::gpu
 		vkCmdSetScissor(frame.cmds, 0, 1, &sci);
 		// maybe bind index buffer
 		// draw[_indexed]/draw_[indexed_]indirect/draw_[indexed_]indirect_count
-		vkCmdDraw(frame.cmds, 3, 1, 0, 0); // todo: dont hardcode this IDIOT
+		vkCmdDraw(frame.cmds, pass.info.graphics.triangle_count * 3, 1, 0, 0); // todo: dont hardcode this IDIOT
 		vkCmdEndRendering(frame.cmds);
 		if(render_into_system_image)
 		{