From 0f920e645441f42d006a3d2635115ff9bcfb37b8 Mon Sep 17 00:00:00 2001
From: Sylpheed RE agent <agent@localhost>
Date: Mon, 31 Aug 2026 06:09:25 +0000
Subject: [PATCH] [RE] Log the blend state of every UI draw

CaptureUiDrawForRE now records RB_BLENDCONTROL0, RB_COLORCONTROL and
RB_COLOR_MASK per draw, raw alongside the decoded src/op/dst fields so a decode
bug here cannot quietly become the answer.

The question it answers: the Godot port composites every UI element with
straight alpha-over and four elements come out too dark against the capture,
with the shortfall correlating with the background. Nothing on the disc selects
a per-element mode, so this reads what the GPU was actually told. Result: the
title-side UI uses two states and one pixel shader -- 0x07010701 (src ONE, dst
1-SRC_ALPHA) for backgrounds, text and buttons, and 0x01010101 (src ONE, dst
ONE, ADDITIVE) for the frame sprites and the rotated sweep strips.
---
 src/xenia/gpu/command_processor.cc | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/src/xenia/gpu/command_processor.cc b/src/xenia/gpu/command_processor.cc
index e350f1132..d389e299c 100644
--- a/src/xenia/gpu/command_processor.cc
+++ b/src/xenia/gpu/command_processor.cc
@@ -296,6 +296,33 @@ void CommandProcessor::CaptureUiDrawForRE(
   if (ps) {
     ui_out << fmt::format(" ps=0x{:016X}", ps->ucode_data_hash());
   }
+  // ── RE: the BLEND STATE of this draw ──────────────────────────────────────
+  // The question this answers: the port's renderer composites every UI element
+  // with straight alpha-over, and four elements (the menu's `ptframe1`/`2` and
+  // EXTRAS' `ptframe3`/`4`) come out too dark against the capture, with the
+  // shortfall correlating with the BACKGROUND rather than with the element's own
+  // contribution — the signature of a blend that scales what is already there.
+  // Nothing on the disc selects a per-element mode (checked in the declaration
+  // entry, every word and bit of the T8aD header, and the keyframe record), so
+  // the remaining candidate is the draw path. This logs what the GPU was
+  // actually told, per draw, rather than inferring it:
+  //   blend=<raw RB_BLENDCONTROL0>  src/dst factors and combine op, colour+alpha
+  //   cc=<raw RB_COLORCONTROL>      alpha test / blend enable
+  //   mask=<raw RB_COLOR_MASK>
+  // Raw values are printed alongside the decoded fields so a decode bug here
+  // cannot silently become the answer.
+  {
+    auto bc = register_file_->Get<reg::RB_BLENDCONTROL>();
+    auto cc = register_file_->Get<reg::RB_COLORCONTROL>();
+    uint32_t mask = register_file_->values[XE_GPU_REG_RB_COLOR_MASK];
+    ui_out << fmt::format(
+        " blend=0x{:08X}[c:src={} op={} dst={} a:src={} op={} dst={}]"
+        " cc=0x{:08X} mask=0x{:X}",
+        bc.value, uint32_t(bc.color_srcblend), uint32_t(bc.color_comb_fcn),
+        uint32_t(bc.color_destblend), uint32_t(bc.alpha_srcblend),
+        uint32_t(bc.alpha_comb_fcn), uint32_t(bc.alpha_destblend), cc.value,
+        mask);
+  }
   if (ps && ps->is_ucode_analyzed()) {
     for (const auto& tb : ps->texture_bindings()) {
       xenos::xe_gpu_texture_fetch_t tf =