Support for drawing in multiple passes

src/r_draw.h

@@ -458,25 +458,34 @@ public:
 	// Number of active threads
 	int num_cores = 1;
 
+	// Range of rows processed this pass
+	int pass_start_y = 0;
+	int pass_end_y = 300;
+
 	uint32_t dc_temp_rgbabuff_rgba[MAXHEIGHT * 4];
 	uint32_t *dc_temp_rgba;
 
 	// Checks if a line is rendered by this thread
 	bool line_skipped_by_thread(int line)
 	{
-		return line % num_cores != core;
+		return line < pass_start_y || line >= pass_end_y || line % num_cores != core;
 	}
 
 	// The number of lines to skip to reach the first line to be rendered by this thread
 	int skipped_by_thread(int first_line)
 	{
-		return (num_cores - (first_line - core) % num_cores) % num_cores;
+		int pass_skip = MAX(pass_start_y - first_line, 0);
+		int core_skip = (num_cores - (first_line + pass_skip - core) % num_cores) % num_cores;
+		return pass_skip + core_skip;
 	}
 
 	// The number of lines to be rendered by this thread
 	int count_for_thread(int first_line, int count)
 	{
-		return (count - skipped_by_thread(first_line) + num_cores - 1) / num_cores;
+		int lines_until_pass_end = MAX(pass_end_y - first_line, 0);
+		count = MIN(count, lines_until_pass_end);
+		int c = (count - skipped_by_thread(first_line) + num_cores - 1) / num_cores;
+		return MAX(c, 0);
 	}
 
 	// Calculate the dest address for the first line to be rendered by this thread
@@ -522,6 +531,8 @@ class DrawerCommandQueue
 
 	bool no_threading = false;
 	DrawerThread single_core_thread;
+	int num_passes = 2;
+	int rows_in_pass = 540;
 
 	void StartThreads();
 	void StopThreads();

src/r_draw_rgba.cpp

@@ -104,12 +104,20 @@ void DrawerCommandQueue::Finish()
 	thread.core = 0;
 	thread.num_cores = queue->threads.size() + 1;
 
+	for (int pass = 0; pass < queue->num_passes; pass++)
+	{
+		thread.pass_start_y = pass * queue->rows_in_pass;
+		thread.pass_end_y = (pass + 1) * queue->rows_in_pass;
+		if (pass + 1 == queue->num_passes)
+			thread.pass_end_y = MAX(thread.pass_end_y, MAXHEIGHT);
+
 		size_t size = queue->active_commands.size();
 		for (size_t i = 0; i < size; i++)
 		{
 			auto &command = queue->active_commands[i];
 			command->Execute(&thread);
 		}
+	}
 
 	// Wait for everyone to finish:
 
@@ -156,12 +164,20 @@ void DrawerCommandQueue::StartThreads()
 				start_lock.unlock();
 
 				// Do the work:
+				for (int pass = 0; pass < queue->num_passes; pass++)
+				{
+					thread->pass_start_y = pass * queue->rows_in_pass;
+					thread->pass_end_y = (pass + 1) * queue->rows_in_pass;
+					if (pass + 1 == queue->num_passes)
+						thread->pass_end_y = MAX(thread->pass_end_y, MAXHEIGHT);
+
 					size_t size = queue->active_commands.size();
 					for (size_t i = 0; i < size; i++)
 					{
 						auto &command = queue->active_commands[i];
 						command->Execute(thread);
 					}
+				}
 
 				// Notify main thread that we finished:
 				std::unique_lock<std::mutex> end_lock(queue->end_mutex);
@@ -1611,6 +1627,79 @@ public:
 			BYTE xshift = yshift - ds_xbits;
 			int xmask = ((1 << ds_xbits) - 1) << ds_ybits;
 
+			int sse_count = count / 4;
+			count -= sse_count * 4;
+
+			if (shade_constants.simple_shade)
+			{
+				SSE_SHADE_SIMPLE_INIT(light);
+
+				while (sse_count--)
+				{
+					spot = ((xfrac >> xshift) & xmask) + (yfrac >> yshift);
+					uint32_t p0 = source[spot];
+					xfrac += xstep;
+					yfrac += ystep;
+
+					spot = ((xfrac >> xshift) & xmask) + (yfrac >> yshift);
+					uint32_t p1 = source[spot];
+					xfrac += xstep;
+					yfrac += ystep;
+
+					spot = ((xfrac >> xshift) & xmask) + (yfrac >> yshift);
+					uint32_t p2 = source[spot];
+					xfrac += xstep;
+					yfrac += ystep;
+
+					spot = ((xfrac >> xshift) & xmask) + (yfrac >> yshift);
+					uint32_t p3 = source[spot];
+					xfrac += xstep;
+					yfrac += ystep;
+
+					// Lookup pixel from flat texture tile
+					__m128i fg = _mm_set_epi32(p3, p2, p1, p0);
+					SSE_SHADE_SIMPLE(fg);
+					_mm_storeu_si128((__m128i*)dest, fg);
+					dest += 4;
+				}
+			}
+			else
+			{
+				SSE_SHADE_INIT(light, shade_constants);
+
+				while (sse_count--)
+				{
+					spot = ((xfrac >> xshift) & xmask) + (yfrac >> yshift);
+					uint32_t p0 = source[spot];
+					xfrac += xstep;
+					yfrac += ystep;
+
+					spot = ((xfrac >> xshift) & xmask) + (yfrac >> yshift);
+					uint32_t p1 = source[spot];
+					xfrac += xstep;
+					yfrac += ystep;
+
+					spot = ((xfrac >> xshift) & xmask) + (yfrac >> yshift);
+					uint32_t p2 = source[spot];
+					xfrac += xstep;
+					yfrac += ystep;
+
+					spot = ((xfrac >> xshift) & xmask) + (yfrac >> yshift);
+					uint32_t p3 = source[spot];
+					xfrac += xstep;
+					yfrac += ystep;
+
+					// Lookup pixel from flat texture tile
+					__m128i fg = _mm_set_epi32(p3, p2, p1, p0);
+					SSE_SHADE(fg, shade_constants);
+					_mm_storeu_si128((__m128i*)dest, fg);
+					dest += 4;
+				}
+			}
+
+			if (count == 0)
+				return;
+
 			do
 			{
 				// Current texture index in u,v.

src/r_drawt_rgba.cpp

@@ -1528,7 +1528,6 @@ public:
 		fracstep = dc_iscale;
 		frac = dc_texturefrac;
 
-		{
 		const BYTE *source = dc_source;
 
 		if (count & 1) {
@@ -1562,7 +1561,6 @@ public:
 			dest += 32;
 		} while (--count);
 	}
-	}
 };
 
 class FillColumnHorizRGBACommand : public DrawerCommand