From 4599527921be131edba2c484171a431db89a1beb Mon Sep 17 00:00:00 2001
From: Sergey Lipskiy <gonetz@ngs.ru>
Date: Thu, 18 Dec 2014 19:38:43 +0600
Subject: [PATCH] Implement flat shading.

---
 OpenGL.cpp | 36 +++++++++++++++++++++++++++++++++++-
 OpenGL.h   |  3 ++-
 gSP.h      |  2 ++
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/OpenGL.cpp b/OpenGL.cpp
index 59ccf0c8..848d655b 100644
--- a/OpenGL.cpp
+++ b/OpenGL.cpp
@@ -267,6 +267,27 @@ void OGLRender::addTriangle(int _v0, int _v1, int _v2)
 	triangles.elements[triangles.num++] = _v0;
 	triangles.elements[triangles.num++] = _v1;
 	triangles.elements[triangles.num++] = _v2;
+
+	if ((gSP.geometryMode & G_SHADE) == 0) {
+		// Prim shading
+		for (u32 i = triangles.num - 3; i < triangles.num; ++i) {
+			SPVertex & vtx = triangles.vertices[triangles.elements[i]];
+			vtx.flat_r = gDP.primColor.r;
+			vtx.flat_g = gDP.primColor.g;
+			vtx.flat_b = gDP.primColor.b;
+			vtx.flat_a = vtx.a;
+		}
+	} else if ((gSP.geometryMode & G_SHADING_SMOOTH) == 0) {
+		// Flat shading
+		SPVertex & vtx0 = triangles.vertices[_v0];
+		for (u32 i = triangles.num - 3; i < triangles.num; ++i) {
+			SPVertex & vtx = triangles.vertices[triangles.elements[i]];
+			vtx.flat_r = vtx0.r;
+			vtx.flat_g = vtx0.g;
+			vtx.flat_b = vtx0.b;
+			vtx.flat_a = vtx.a;
+		}
+	}
 }
 
 #define ORKIN_BLENDMODE
@@ -687,10 +708,17 @@ void OGLRender::_prepareDrawTriangle(bool _dma)
 		_setTexCoordArrays();
 	}
 
+	const bool updateColorArrays = m_bFlatColors != (!RSP.bLLE && (gSP.geometryMode & G_SHADING_SMOOTH) == 0);
+	if (updateColorArrays)
+		m_bFlatColors = !m_bFlatColors;
+
 	if (updateArrays) {
 		SPVertex * pVtx = _dma ? triangles.dmaVertices.data() : &triangles.vertices[0];
 		glVertexAttribPointer(SC_POSITION, 4, GL_FLOAT, GL_FALSE, sizeof(SPVertex), &pVtx->x);
-		glVertexAttribPointer(SC_COLOR, 4, GL_FLOAT, GL_FALSE, sizeof(SPVertex), &pVtx->r);
+		if (m_bFlatColors)
+			glVertexAttribPointer(SC_COLOR, 4, GL_FLOAT, GL_FALSE, sizeof(SPVertex), &pVtx->flat_r);
+		else
+			glVertexAttribPointer(SC_COLOR, 4, GL_FLOAT, GL_FALSE, sizeof(SPVertex), &pVtx->r);
 		glVertexAttribPointer(SC_TEXCOORD0, 2, GL_FLOAT, GL_FALSE, sizeof(SPVertex), &pVtx->s);
 		if (config.enableHWLighting) {
 			glEnableVertexAttribArray(SC_NUMLIGHTS);
@@ -701,6 +729,12 @@ void OGLRender::_prepareDrawTriangle(bool _dma)
 		_updateViewport();
 		glEnable(GL_SCISSOR_TEST);
 		currentCombiner()->updateRenderState();
+	} else if (updateColorArrays) {
+		SPVertex * pVtx = _dma ? triangles.dmaVertices.data() : &triangles.vertices[0];
+		if (m_bFlatColors)
+			glVertexAttribPointer(SC_COLOR, 4, GL_FLOAT, GL_FALSE, sizeof(SPVertex), &pVtx->flat_r);
+		else
+			glVertexAttribPointer(SC_COLOR, 4, GL_FLOAT, GL_FALSE, sizeof(SPVertex), &pVtx->r);
 	}
 
 	currentCombiner()->updateColors();
diff --git a/OpenGL.h b/OpenGL.h
index 3a686a21..7e948dca 100644
--- a/OpenGL.h
+++ b/OpenGL.h
@@ -87,7 +87,7 @@ public:
 #endif // __TRIBUFFER_OPT
 
 private:
-	OGLRender() : m_bImageTexture(false) {}
+	OGLRender() : m_bImageTexture(false), m_bFlatColors(false) {}
 	OGLRender(const OGLRender &);
 	friend class OGLVideo;
 
@@ -133,6 +133,7 @@ private:
 	RENDER_STATE m_renderState;
 	GLVertex m_rect[4];
 	bool m_bImageTexture;
+	bool m_bFlatColors;
 };
 
 class OGLVideo
diff --git a/gSP.h b/gSP.h
index 90ab7f30..39b1805c 100644
--- a/gSP.h
+++ b/gSP.h
@@ -21,6 +21,7 @@ if \
 ( \
 	( \
 		 (video().getRender().getTrianglesCount() > 1000) || \
+		 ((gSP.geometryMode & G_SHADING_SMOOTH) == 0) || \
 		 ( \
 			 (RSP.nextCmd != G_NOOP) && \
 			 (RSP.nextCmd != G_RDPNOOP) && \
@@ -73,6 +74,7 @@ struct SPVertex
 	f32 x, y, z, w;
 	f32 nx, ny, nz, __pad0;
 	f32 r, g, b, a;
+	f32 flat_r, flat_g, flat_b, flat_a;
 	f32 s, t;
 	u8 HWLight;
 	s16 flag;