From f019817f8f6452dec784d8217ef102231319d26c Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Wed, 30 Oct 2019 00:23:09 -0300
Subject: gl_rasterizer: Emulate viewport flipping with ARB_clip_control

Emulates negative y viewports with ARB_clip_control. This allows us to
more easily emulated pipelines with tessellation and/or geometry shader
stages. It also avoids corrupting games with transform feedbacks and
negative viewports (gl_Position.y was being modified).
---
 src/video_core/renderer_opengl/gl_state.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'src/video_core/renderer_opengl/gl_state.cpp')

diff --git a/src/video_core/renderer_opengl/gl_state.cpp b/src/video_core/renderer_opengl/gl_state.cpp
index f25148362..ccbe5912e 100644
--- a/src/video_core/renderer_opengl/gl_state.cpp
+++ b/src/video_core/renderer_opengl/gl_state.cpp
@@ -410,6 +410,12 @@ void OpenGLState::ApplyAlphaTest() {
     }
 }
 
+void OpenGLState::ApplyClipControl() {
+    if (UpdateValue(cur_state.clip_control.origin, clip_control.origin)) {
+        glClipControl(clip_control.origin, GL_NEGATIVE_ONE_TO_ONE);
+    }
+}
+
 void OpenGLState::ApplyTextures() {
     if (const auto update = UpdateArray(cur_state.textures, textures)) {
         glBindTextures(update->first, update->second, textures.data() + update->first);
@@ -453,6 +459,7 @@ void OpenGLState::Apply() {
     ApplyImages();
     ApplyPolygonOffset();
     ApplyAlphaTest();
+    ApplyClipControl();
 }
 
 void OpenGLState::EmulateViewportWithScissor() {
-- 
cgit v1.2.3