From 431313156a80592216a7bed2ec17988fa0495987 Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <mclaughc@outlook.com>
Date: Sat, 5 Oct 2019 14:36:48 +1000
Subject: [PATCH] GPU: Fix invalid rectangle passed to glScissor

---
 src/core/gpu_hw.cpp               |  8 ++++----
 src/core/gpu_hw_opengl.cpp        | 27 +++++++++++++++++----------
 src/core/gpu_hw_opengl.h          |  1 +
 src/duckstation/sdl_interface.cpp |  6 ++++--
 4 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/src/core/gpu_hw.cpp b/src/core/gpu_hw.cpp
index 80cd5ecdc..1d563d5f1 100644
--- a/src/core/gpu_hw.cpp
+++ b/src/core/gpu_hw.cpp
@@ -141,10 +141,10 @@ void GPU_HW::LoadVertices(RenderCommand rc, u32 num_vertices)
 
 void GPU_HW::CalcScissorRect(int* left, int* top, int* right, int* bottom)
 {
-  *left = m_drawing_area.left * s32(m_resolution_scale);
-  *right = (m_drawing_area.right + 1) * s32(m_resolution_scale);
-  *top = m_drawing_area.top * s32(m_resolution_scale);
-  *bottom = (m_drawing_area.bottom + 1) * s32(m_resolution_scale);
+  *left = m_drawing_area.left * m_resolution_scale;
+  *right = std::max<u32>((m_drawing_area.right + 1) * m_resolution_scale, *left + 1);
+  *top = m_drawing_area.top * m_resolution_scale;
+  *bottom = std::max<u32>((m_drawing_area.bottom + 1) * m_resolution_scale, *top + 1);
 }
 
 static void DefineMacro(std::stringstream& ss, const char* name, bool enabled)
diff --git a/src/core/gpu_hw_opengl.cpp b/src/core/gpu_hw_opengl.cpp
index c0e4cbc0f..675cbdae3 100644
--- a/src/core/gpu_hw_opengl.cpp
+++ b/src/core/gpu_hw_opengl.cpp
@@ -396,20 +396,27 @@ void GPU_HW_OpenGL::SetDrawState()
       glBlendFuncSeparate(GL_ONE, GL_SRC_ALPHA, GL_ONE, GL_ZERO);
     }
   }
+
+  if (m_drawing_area_changed)
+  {
+    m_drawing_area_changed = false;
+
+    int left, top, right, bottom;
+    CalcScissorRect(&left, &top, &right, &bottom);
+
+    const int width = right - left;
+    const int height = bottom - top;
+    const int x = left;
+    const int y = m_vram_texture->GetHeight() - bottom;
+
+    Log_DebugPrintf("SetScissor: (%d-%d, %d-%d)", x, x + width, y, y + height);
+    glScissor(x, y, width, height);
+  }
 }
 
 void GPU_HW_OpenGL::UpdateDrawingArea()
 {
-  int left, top, right, bottom;
-  CalcScissorRect(&left, &top, &right, &bottom);
-
-  const int width = right - left;
-  const int height = bottom - top;
-  const int x = left;
-  const int y = m_vram_texture->GetHeight() - bottom;
-
-  Log_DebugPrintf("SetScissor: (%d-%d, %d-%d)", x, x + width, y, y + height);
-  glScissor(x, y, width, height);
+  m_drawing_area_changed = true;
 }
 
 void GPU_HW_OpenGL::UpdateDisplay()
diff --git a/src/core/gpu_hw_opengl.h b/src/core/gpu_hw_opengl.h
index 0dec54cdd..a3fb9bd95 100644
--- a/src/core/gpu_hw_opengl.h
+++ b/src/core/gpu_hw_opengl.h
@@ -73,6 +73,7 @@ private:
   bool m_vram_read_texture_dirty = true;
   bool m_last_transparency_enable = false;
   TransparencyMode m_last_transparency_mode = TransparencyMode::BackgroundMinusForeground;
+  bool m_drawing_area_changed = true;
 
   std::array<std::array<std::array<std::array<GL::Program, 2>, 3>, 2>, 2> m_render_programs;
   GL::Program m_reinterpret_rgb8_program;
diff --git a/src/duckstation/sdl_interface.cpp b/src/duckstation/sdl_interface.cpp
index 015b33462..02b6e8978 100644
--- a/src/duckstation/sdl_interface.cpp
+++ b/src/duckstation/sdl_interface.cpp
@@ -98,12 +98,14 @@ bool SDLInterface::CreateGLContext()
     return false;
   }
 
+#if 0
   if (GLAD_GL_KHR_debug)
   {
     glad_glDebugMessageCallbackKHR(GLDebugCallback, nullptr);
-    // glEnable(GL_DEBUG_OUTPUT);
-    // glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
+    glEnable(GL_DEBUG_OUTPUT);
+    glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
   }
+#endif
 
   SDL_GL_SetSwapInterval(0);
   return true;