From 38d09ce35c924fce5e59b112ca8d671b7bf8fad8 Mon Sep 17 00:00:00 2001
From: vladislavbelov <vladislavbelov@wildfiregames.com>
Date: Sun, 29 Oct 2017 23:41:59 +0000
Subject: [PATCH] Adds a perspective matrix, refracts a matrix projection setup
 to prepare for an isometric view.

Reviewed By: wraitii
Differential Revision: https://code.wildfiregames.com/D971
This was SVN commit r20377.
---
 source/graphics/Camera.cpp | 24 ++++++++----------------
 source/maths/Matrix3D.cpp  | 33 ++++++++++++++++++++++++---------
 source/maths/Matrix3D.h    |  6 ++++--
 3 files changed, 36 insertions(+), 27 deletions(-)

diff --git a/source/graphics/Camera.cpp b/source/graphics/Camera.cpp
index 5cf69d154d..ed24da15f5 100644
--- a/source/graphics/Camera.cpp
+++ b/source/graphics/Camera.cpp
@@ -54,27 +54,19 @@ void CCamera::SetProjection(float nearp, float farp, float fov)
 	m_FarPlane = farp;
 	m_FOV = fov;
 
-	float aspect = (float)m_ViewPort.m_Width/(float)m_ViewPort.m_Height;
-	float f = 1.0f/tanf(m_FOV/2);
-
-	m_ProjMat.SetZero ();
-	m_ProjMat._11 = f/aspect;
-	m_ProjMat._22 = f;
-	m_ProjMat._33 = -(m_FarPlane+m_NearPlane)/(m_NearPlane-m_FarPlane);
-	m_ProjMat._34 = 2*m_FarPlane*m_NearPlane/(m_NearPlane-m_FarPlane);
-	m_ProjMat._43 = 1.0f;
+	const float aspect = static_cast<float>(m_ViewPort.m_Width) / static_cast<float>(m_ViewPort.m_Height);
+	m_ProjMat.SetPerspective(m_FOV, aspect, m_NearPlane, m_FarPlane);
 }
 
 void CCamera::SetProjectionTile(int tiles, int tile_x, int tile_y)
 {
+	const float aspect = static_cast<float>(m_ViewPort.m_Width) / static_cast<float>(m_ViewPort.m_Height);
+	const float f = 1.f / tanf(m_FOV / 2.f);
 
-	float aspect = (float)m_ViewPort.m_Width/(float)m_ViewPort.m_Height;
-	float f = 1.0f/tanf(m_FOV/2);
-
-	m_ProjMat._11 = tiles*f/aspect;
-	m_ProjMat._22 = tiles*f;
-	m_ProjMat._13 = -(1-tiles + 2*tile_x);
-	m_ProjMat._23 = -(1-tiles + 2*tile_y);
+	m_ProjMat._11 = tiles * f / aspect;
+	m_ProjMat._22 = tiles * f;
+	m_ProjMat._13 = -(1 - tiles + 2 * tile_x);
+	m_ProjMat._23 = -(1 - tiles + 2 * tile_y);
 }
 
 //Updates the frustum planes. Should be called
diff --git a/source/maths/Matrix3D.cpp b/source/maths/Matrix3D.cpp
index ef12f6f425..589da4dab8 100644
--- a/source/maths/Matrix3D.cpp
+++ b/source/maths/Matrix3D.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2010 Wildfire Games.
+/* Copyright (C) 2017 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -36,7 +36,7 @@ void CMatrix3D::SetIdentity ()
 }
 
 //Sets the zero matrix
-void CMatrix3D::SetZero ()
+void CMatrix3D::SetZero()
 {
 	_11=0.0f; _12=0.0f; _13=0.0f; _14=0.0f;
 	_21=0.0f; _22=0.0f; _23=0.0f; _24=0.0f;
@@ -44,15 +44,30 @@ void CMatrix3D::SetZero ()
 	_41=0.0f; _42=0.0f; _43=0.0f; _44=0.0f;
 }
 
-void CMatrix3D::SetOrtho (float l, float r, float b, float t, float n, float f)
+void CMatrix3D::SetOrtho(float left, float right, float bottom, float top, float near, float far)
 {
 	// Based on OpenGL spec
-	*this = CMatrix3D(
-		2/(r-l), 0, 0, -(r+l)/(r-l),
-		0, 2/(t-b), 0, -(t+b)/(t-b),
-		0, 0, -2/(f-n), -(f+n)/(f-n),
-		0, 0, 0, 1
-	);
+	SetZero();
+	_11 = 2 / (right - left);
+	_22 = 2 / (top - bottom);
+	_33 = -2 / (far - near);
+	_44 = 1;
+
+	_14 = -(right + left) / (right - left);
+	_24 = -(top + bottom) / (top - bottom);
+	_34 = -(far + near) / (far - near);
+}
+
+void CMatrix3D::SetPerspective(float fov, float aspect, float near, float far)
+{
+	const float f = 1.f / tanf(fov / 2.f);
+
+	SetZero();
+	_11 = f / aspect;
+	_22 = f;
+	_33 = -(far + near) / (near - far);
+	_34 = 2 * far * near / (near - far);
+	_43 = 1;
 }
 
 //The following clear the matrix and set the
diff --git a/source/maths/Matrix3D.h b/source/maths/Matrix3D.h
index 77cb290f9a..d86ad096fa 100644
--- a/source/maths/Matrix3D.h
+++ b/source/maths/Matrix3D.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2010 Wildfire Games.
+/* Copyright (C) 2017 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -182,7 +182,9 @@ public:
 	// set this matrix to the zero matrix
 	void SetZero();
 	// set this matrix to the orthogonal projection matrix (as with glOrtho)
-	void SetOrtho(float l, float r, float b, float t, float n, float f);
+	void SetOrtho(float left, float right, float bottom, float top, float near, float far);
+	// set this matrix to the perspective projection matrix
+	void SetPerspective(float fov, float aspect, float near, float far);
 
 	// concatenate arbitrary matrix onto this matrix
 	void Concatenate(const CMatrix3D& m)