From c7b2f9d1d2e70b694c0341ce285a81da7a2c9554 Mon Sep 17 00:00:00 2001
From: Gregory Hainaut <gregory.hainaut@gmail.com>
Date: Sat, 15 Aug 2015 13:20:54 +0200
Subject: [PATCH] gsdx-ogl: setup fbo to always write to first buffer

GL_NONE was kind of useless because nothing was attached anyway
---
 plugins/GSdx/GSDeviceOGL.cpp   | 16 ++++++----------
 plugins/GSdx/GSDeviceOGL.h     |  1 -
 plugins/GSdx/GSRendererOGL.cpp |  2 --
 3 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/plugins/GSdx/GSDeviceOGL.cpp b/plugins/GSdx/GSDeviceOGL.cpp
index 88e1692383..876af1bee9 100644
--- a/plugins/GSdx/GSDeviceOGL.cpp
+++ b/plugins/GSdx/GSDeviceOGL.cpp
@@ -205,6 +205,12 @@ bool GSDeviceOGL::Create(GSWnd* wnd)
 	m_shader = new GSShaderOGL(!!theApp.GetConfig("debug_glsl_shader", 0));
 
 	gl_GenFramebuffers(1, &m_fbo);
+	// Always write to the first buffer
+	OMSetFBO(m_fbo);
+	GLenum target[1] = {GL_COLOR_ATTACHMENT0};
+	gl_DrawBuffers(1, target);
+	OMSetFBO(0);
+
 	gl_GenFramebuffers(1, &m_fbo_read);
 	// Always read from the first buffer
 	gl_BindFramebuffer(GL_READ_FRAMEBUFFER, m_fbo_read);
@@ -1211,9 +1217,7 @@ void GSDeviceOGL::SetupDATE(GSTexture* rt, GSTexture* ds, const GSVertexPT1* ver
 	if (GLState::blend) {
 		glDisable(GL_BLEND);
 	}
-	// normally ok without any RT if GL_ARB_framebuffer_no_attachments is supported (minus driver bug)
 	OMSetRenderTargets(NULL, ds, &GLState::scissor);
-	OMSetColorMaskState(); // TODO: likely useless
 
 	// ia
 
@@ -1324,12 +1328,6 @@ void GSDeviceOGL::OMSetFBO(GLuint fbo)
 	}
 }
 
-void GSDeviceOGL::OMSetWriteBuffer(GLenum buffer)
-{
-	GLenum target[1] = {buffer};
-	gl_DrawBuffers(1, target);
-}
-
 void GSDeviceOGL::OMSetDepthStencilState(GSDepthStencilOGL* dss)
 {
 	dss->SetupDepth();
@@ -1394,10 +1392,8 @@ void GSDeviceOGL::OMSetRenderTargets(GSTexture* rt, GSTexture* ds, const GSVecto
 	if (rt == NULL || !RT->IsBackbuffer()) {
 		OMSetFBO(m_fbo);
 		if (rt) {
-			OMSetWriteBuffer();
 			OMAttachRt(RT);
 		} else {
-			OMSetWriteBuffer(GL_NONE);
 			OMAttachRt();
 		}
 
diff --git a/plugins/GSdx/GSDeviceOGL.h b/plugins/GSdx/GSDeviceOGL.h
index 189d102229..dd201ede62 100644
--- a/plugins/GSdx/GSDeviceOGL.h
+++ b/plugins/GSdx/GSDeviceOGL.h
@@ -529,7 +529,6 @@ class GSDeviceOGL : public GSDevice
 	void OMSetDepthStencilState(GSDepthStencilOGL* dss);
 	void OMSetBlendState(uint8 blend_index = 0, uint8 blend_factor = 0, bool is_blend_constant = false);
 	void OMSetRenderTargets(GSTexture* rt, GSTexture* ds, const GSVector4i* scissor = NULL);
-	void OMSetWriteBuffer(GLenum buffer = GL_COLOR_ATTACHMENT0);
 	void OMSetColorMaskState(OMColorMaskSelector sel = OMColorMaskSelector());
 
 
diff --git a/plugins/GSdx/GSRendererOGL.cpp b/plugins/GSdx/GSRendererOGL.cpp
index c3b9e098a0..8439f32903 100644
--- a/plugins/GSdx/GSRendererOGL.cpp
+++ b/plugins/GSdx/GSRendererOGL.cpp
@@ -906,13 +906,11 @@ void GSRendererOGL::DrawPrims(GSTexture* rt, GSTexture* ds, GSTextureCache::Sour
 
 		// Don't write anything on the color buffer
 		// Neither in the depth buffer
-		dev->OMSetWriteBuffer(GL_NONE);
 		glDepthMask(false);
 		// Compute primitiveID max that pass the date test
 		SendDraw(false);
 
 		// Ask PS to discard shader above the primitiveID max
-		dev->OMSetWriteBuffer();
 		glDepthMask(GLState::depth_mask);
 
 		ps_sel.date = 3;