From 6f70a901f84e58ccba2f3c2bf2572028b255955d Mon Sep 17 00:00:00 2001
From: vladislavbelov <vladislavbelov@wildfiregames.com>
Date: Fri, 12 Jun 2020 20:52:18 +0000
Subject: [PATCH] Remove duplicated call in tile rendering for TerrainOverlay.

Patch By: vinhig
Reviewed By: wraitii
Differential Revision: https://code.wildfiregames.com/D2811
This was SVN commit r23767.
---
 .../public/gui/credits/texts/programming.json |  1 +
 source/renderer/TerrainOverlay.cpp            | 38 ++++++++++---------
 2 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/binaries/data/mods/public/gui/credits/texts/programming.json b/binaries/data/mods/public/gui/credits/texts/programming.json
index 3c51dc4cf4..61dd17c4e2 100644
--- a/binaries/data/mods/public/gui/credits/texts/programming.json
+++ b/binaries/data/mods/public/gui/credits/texts/programming.json
@@ -246,6 +246,7 @@
 				{ "nick": "user1", "name": "A. C." },
 				{ "nick": "usey11" },
 				{ "nick": "vincent_c", "name": "Vincent Cheng" },
+				{ "nick": "vinhig", "name": "Vincent Higginson" },
 				{ "nick": "vladislavbelov", "name": "Vladislav Belov" },
 				{ "nick": "voroskoi" },
 				{ "nick": "vts", "name": "Jeroen DR" },
diff --git a/source/renderer/TerrainOverlay.cpp b/source/renderer/TerrainOverlay.cpp
index 3d487f3a75..03591574bd 100644
--- a/source/renderer/TerrainOverlay.cpp
+++ b/source/renderer/TerrainOverlay.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2019 Wildfire Games.
+/* Copyright (C) 2020 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -163,9 +163,9 @@ void TerrainOverlay::RenderTile(const CColor& color, bool draw_hidden)
 
 void TerrainOverlay::RenderTile(const CColor& color, bool draw_hidden, ssize_t i, ssize_t j)
 {
-	// TODO: if this is unpleasantly slow, make it much more efficient
-	// (e.g. buffering data and making a single draw call? or at least
-	// far fewer calls than it makes now)
+	// TODO: unnecessary computation calls has been removed but we should use
+	// a vertex buffer or a vertex shader with a texture.
+	// Not sure if it's possible on old OpenGL.
 
 	if (draw_hidden)
 	{
@@ -184,28 +184,32 @@ void TerrainOverlay::RenderTile(const CColor& color, bool draw_hidden, ssize_t i
 
 	glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
 
-	CVector3D pos;
+	CVector3D pos[2][2];
+	for (int di = 0; di < 2; ++di)
+		for (int dj = 0; dj < 2; ++dj)
+			m_Terrain->CalcPosition(i + di, j + dj, pos[di][dj]);
+
 	glBegin(GL_TRIANGLES);
 		glColor4fv(color.FloatArray());
 		if (m_Terrain->GetTriangulationDir(i, j))
 		{
-			m_Terrain->CalcPosition(i,   j,   pos); glVertex3fv(pos.GetFloatArray());
-			m_Terrain->CalcPosition(i+1, j,   pos); glVertex3fv(pos.GetFloatArray());
-			m_Terrain->CalcPosition(i,   j+1, pos); glVertex3fv(pos.GetFloatArray());
+			glVertex3fv(pos[0][0].GetFloatArray());
+			glVertex3fv(pos[1][0].GetFloatArray());
+			glVertex3fv(pos[0][1].GetFloatArray());
 
-			m_Terrain->CalcPosition(i+1, j,   pos); glVertex3fv(pos.GetFloatArray());
-			m_Terrain->CalcPosition(i+1, j+1, pos); glVertex3fv(pos.GetFloatArray());
-			m_Terrain->CalcPosition(i,   j+1, pos); glVertex3fv(pos.GetFloatArray());
+			glVertex3fv(pos[1][0].GetFloatArray());
+			glVertex3fv(pos[1][1].GetFloatArray());
+			glVertex3fv(pos[0][1].GetFloatArray());
 		}
 		else
 		{
-			m_Terrain->CalcPosition(i,   j,   pos); glVertex3fv(pos.GetFloatArray());
-			m_Terrain->CalcPosition(i+1, j,   pos); glVertex3fv(pos.GetFloatArray());
-			m_Terrain->CalcPosition(i+1, j+1, pos); glVertex3fv(pos.GetFloatArray());
+			glVertex3fv(pos[0][0].GetFloatArray());
+			glVertex3fv(pos[1][0].GetFloatArray());
+			glVertex3fv(pos[1][1].GetFloatArray());
 
-			m_Terrain->CalcPosition(i+1, j+1, pos); glVertex3fv(pos.GetFloatArray());
-			m_Terrain->CalcPosition(i,   j+1, pos); glVertex3fv(pos.GetFloatArray());
-			m_Terrain->CalcPosition(i,   j,   pos); glVertex3fv(pos.GetFloatArray());
+			glVertex3fv(pos[1][1].GetFloatArray());
+			glVertex3fv(pos[0][1].GetFloatArray());
+			glVertex3fv(pos[0][0].GetFloatArray());
 		}
 	glEnd();