From 0172f220ed72ca72f1c082e72d538ca602581404 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Tue, 2 Dec 2025 20:02:28 +1000
Subject: [PATCH] GPU/HW: Draw small fill sprites with software if TC is
 enabled

Wild Arms 2 clears out the sprite area of VRAM, then uploads new
sprites. The clears were not counting as fills before, because
they did not meet the page threshold.

It's not worth risking treating all untextured sprite draws as
clears, so instead just draw it with software as well to ensure
the local copy of VRAM is cleared.
---
 src/core/gpu_hw.cpp | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/core/gpu_hw.cpp b/src/core/gpu_hw.cpp
index c00b30570..2370ead8b 100644
--- a/src/core/gpu_hw.cpp
+++ b/src/core/gpu_hw.cpp
@@ -2751,12 +2751,27 @@ void GPU_HW::DrawLine(const GPUBackendDrawCommand* cmd, const GSVector4 bounds,
 void GPU_HW::DrawSprite(const GPUBackendDrawRectangleCommand* cmd)
 {
   // Treat non-textured sprite draws as fills, so we don't break the TC on framebuffer clears.
-  if (m_use_texture_cache && !cmd->transparency_enable && !cmd->shading_enable && !cmd->texture_enable && cmd->x >= 0 &&
-      cmd->y >= 0 && cmd->width >= TEXTURE_PAGE_WIDTH && cmd->height >= TEXTURE_PAGE_HEIGHT &&
+  bool draw_with_software_renderer = m_draw_with_software_renderer;
+  if (m_use_texture_cache && !cmd->transparency_enable && !cmd->shading_enable && !cmd->texture_enable &&
+      !cmd->check_mask_before_draw && cmd->x >= 0 && cmd->y >= 0 &&
       (static_cast<u32>(cmd->x) + cmd->width) <= VRAM_WIDTH && (static_cast<u32>(cmd->y) + cmd->height) <= VRAM_HEIGHT)
   {
-    FillVRAM(cmd->x, cmd->y, cmd->width, cmd->height, cmd->color, cmd->interlaced_rendering, cmd->active_line_lsb);
-    return;
+    // For small fills, we don't go down the FillVRAM() path as that will wipe out the drawn state on the pages, as this
+    // has the potential to cause false positives. Instead we just throw the draw down the software path in addition.
+    // Test case: Wild Arms 2 player sprites.
+    if (cmd->width <= TEXTURE_PAGE_WIDTH && cmd->height <= TEXTURE_PAGE_HEIGHT)
+    {
+      GL_INS_FMT("Also drawing non-textured sprite with software at {},{} size {}x{}", cmd->x, cmd->y, cmd->width,
+                 cmd->height);
+      draw_with_software_renderer = true;
+    }
+    else
+    {
+      GL_INS_FMT("Treating non-textured sprite as VRAM fill at {},{} size {}x{}", cmd->x, cmd->y, cmd->width,
+                 cmd->height);
+      FillVRAM(cmd->x, cmd->y, cmd->width, cmd->height, cmd->color, cmd->interlaced_rendering, cmd->active_line_lsb);
+      return;
+    }
   }
 
   const GSVector2i pos = GSVector2i::load<true>(&cmd->x);
@@ -2845,7 +2860,7 @@ void GPU_HW::DrawSprite(const GPUBackendDrawRectangleCommand* cmd)
 
   AddDrawnRectangle(clamped_rect);
 
-  if (m_draw_with_software_renderer)
+  if (draw_with_software_renderer)
   {
     const GPU_SW_Rasterizer::DrawRectangleFunction DrawFunction = GPU_SW_Rasterizer::GetDrawRectangleFunction(
       cmd->texture_enable, cmd->raw_texture_enable, cmd->transparency_enable);