From 8f1d724f4c0c9601bd5fd9c9343a1020e577d63b Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Sun, 5 Nov 2023 14:10:37 +1000
Subject: [PATCH] Postprocesing/FX: Add BUFFER_COLOR_BIT_DEPTH and random
 source

---
 src/util/postprocessing_shader_fx.cpp | 27 +++++++++++++++++++++++++++
 src/util/postprocessing_shader_fx.h   |  7 +++++++
 2 files changed, 34 insertions(+)

diff --git a/src/util/postprocessing_shader_fx.cpp b/src/util/postprocessing_shader_fx.cpp
index c3bddef5d..c5804217a 100644
--- a/src/util/postprocessing_shader_fx.cpp
+++ b/src/util/postprocessing_shader_fx.cpp
@@ -329,6 +329,7 @@ bool PostProcessing::ReShadeFXShader::CreateModule(s32 buffer_width, s32 buffer_
   pp.add_macro_definition("BUFFER_HEIGHT", std::to_string(buffer_height));
   pp.add_macro_definition("BUFFER_RCP_WIDTH", std::to_string(1.0f / static_cast<float>(buffer_width)));
   pp.add_macro_definition("BUFFER_RCP_HEIGHT", std::to_string(1.0f / static_cast<float>(buffer_height)));
+  pp.add_macro_definition("BUFFER_COLOR_BIT_DEPTH", "32");
 
   switch (GetRenderAPI())
   {
@@ -683,6 +684,19 @@ bool PostProcessing::ReShadeFXShader::GetSourceOption(const reshadefx::uniform_i
       *si = SourceOptionType::MousePoint;
       return true;
     }
+    else if (source == "random")
+    {
+      if ((!ui.type.is_floating_point() && !ui.type.is_integral()) || ui.type.components() != 1)
+      {
+        Error::SetString(error, fmt::format("Unexpected type '{}' ({} components) for random source in uniform '{}'",
+                                            ui.type.description(), ui.type.components(), ui.name));
+        return false;
+      }
+
+      // TODO: This is missing min/max handling.
+      *si = (ui.type.base == reshadefx::type::t_float) ? SourceOptionType::RandomF : SourceOptionType::Random;
+      return true;
+    }
     else if (source == "overlay_active" || source == "has_depth")
     {
       *si = SourceOptionType::Zero;
@@ -1241,6 +1255,19 @@ bool PostProcessing::ReShadeFXShader::Apply(GPUTexture* input, GPUFramebuffer* f
         }
         break;
 
+        case SourceOptionType::Random:
+        {
+          const s32 rv = m_random() % 32767; // reshade uses rand(), which on some platforms has a 0x7fff maximum.
+          std::memcpy(dst, &rv, sizeof(rv));
+        }
+        break;
+        case SourceOptionType::RandomF:
+        {
+          const float rv = (m_random() - m_random.min()) / static_cast<float>(m_random.max() - m_random.min());
+          std::memcpy(dst, &rv, sizeof(rv));
+        }
+        break;
+
         case SourceOptionType::BufferWidth:
         case SourceOptionType::BufferHeight:
         {
diff --git a/src/util/postprocessing_shader_fx.h b/src/util/postprocessing_shader_fx.h
index cbbd8f06f..2d09e43ce 100644
--- a/src/util/postprocessing_shader_fx.h
+++ b/src/util/postprocessing_shader_fx.h
@@ -10,6 +10,8 @@
 // reshadefx
 #include "effect_module.hpp"
 
+#include <random>
+
 class Error;
 
 namespace PostProcessing {
@@ -46,6 +48,8 @@ private:
     FrameCountF,
     PingPong,
     MousePoint,
+    Random,
+    RandomF,
     BufferWidth,
     BufferHeight,
     BufferWidthF,
@@ -117,6 +121,9 @@ private:
 
   Common::Timer m_frame_timer;
   u32 m_frame_count = 0;
+
+  // Specifically using a fixed seed, so that it's consistent from run-to-run.
+  std::mt19937 m_random{0x1337};
 };
 
 } // namespace PostProcessing
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