From 77832dbcb4862aef45381eb99250309bfc061e2a Mon Sep 17 00:00:00 2001
From: tosh <tosh@monster.hlan>
Date: Wed, 17 Apr 2013 20:53:24 +0200
Subject: [PATCH] makes FieldOfView store the view matrix instead of its
 inverse

---
 interface/src/FieldOfView.cpp | 21 ++++++++++++++-----
 interface/src/FieldOfView.h   | 39 ++++++++++++++++++++++++++---------
 2 files changed, 45 insertions(+), 15 deletions(-)

diff --git a/interface/src/FieldOfView.cpp b/interface/src/FieldOfView.cpp
index c255d7232f..0aef91b0ab 100644
--- a/interface/src/FieldOfView.cpp
+++ b/interface/src/FieldOfView.cpp
@@ -1,6 +1,6 @@
 //
 // FieldOfView.cpp
-// interface
+// hifi
 //
 // Created by Tobias Schwinger on 3/21/13.
 // Copyright (c) 2013 High Fidelity, Inc. All rights reserved.
@@ -16,7 +16,7 @@
 using namespace glm;
 
 FieldOfView::FieldOfView() :
-    _matOrientation(mat4(1.0f)),
+    _matView(mat4(1.0f)),
     _vecBoundsLow(vec3(-1.0f,-1.0f,-1.0f)),
     _vecBoundsHigh(vec3(1.0f,1.0f,1.0f)),
     _valWidth(256.0f),
@@ -26,6 +26,17 @@ FieldOfView::FieldOfView() :
     _enmAspectBalancing(expose_less) {
 }
 
+FieldOfView& FieldOfView::setOrientation(mat4 const& matrix) {
+
+    _matView = affineInverse(matrix);
+    return *this;
+}
+
+mat4 FieldOfView::getOrientation() const {
+
+    return affineInverse(_matView);
+}
+
 mat4 FieldOfView::getViewerScreenXform() const {
 
     mat4 projection;
@@ -48,14 +59,14 @@ mat4 FieldOfView::getViewerScreenXform() const {
 
 mat4 FieldOfView::getWorldViewerXform() const {
 
-    return translate(affineInverse(_matOrientation),
+    return translate(_matView,
             vec3(0.0f, 0.0f, -_vecBoundsHigh.z) );
 }
 
 mat4 FieldOfView::getWorldScreenXform() const {
 
     return translate(
-            getViewerScreenXform() * affineInverse(_matOrientation),
+            getViewerScreenXform() * _matView,
             vec3(0.0f, 0.0f, -_vecBoundsHigh.z) );
 }
 
@@ -65,7 +76,7 @@ mat4 FieldOfView::getViewerWorldXform() const {
 
     return translate(
             translate(mat4(1.0f), n_translate) 
-                * _matOrientation, -n_translate );
+                * affineInverse(_matView), -n_translate );
 }
 
 float FieldOfView::getPixelSize() const {
diff --git a/interface/src/FieldOfView.h b/interface/src/FieldOfView.h
index f4caf582c2..82d5c79b6b 100644
--- a/interface/src/FieldOfView.h
+++ b/interface/src/FieldOfView.h
@@ -1,22 +1,30 @@
 //
 // FieldOfView.h
-// interface
+// hifi
 //
 // Created by Tobias Schwinger on 3/21/13.
 // Copyright (c) 2013 High Fidelity, Inc. All rights reserved.
 //
 
-#ifndef __interface__FieldOfView__
-#define __interface__FieldOfView__
+#ifndef __hifi__FieldOfView__
+#define __hifi__FieldOfView__
 
 #include <glm/glm.hpp>
 
 // 
 // Viewing parameter encapsulation.
-// 
+//
+// Once configured provides transformation matrices between different coordinate spaces, such as
+//
+//   o world space, 
+//   o viewer space (orientation of local viewer, no projective transforms), and
+//   o screen space (as Viewer space + projection).
+//
+// Also provides information about the mapping of the screen space coordinates onto the screen.
+//
 class FieldOfView {
 
-        glm::mat4   _matOrientation;
+        glm::mat4   _matView;
         glm::vec3   _vecBoundsLow;
         glm::vec3   _vecBoundsHigh;
         float       _valWidth;
@@ -33,7 +41,9 @@ class FieldOfView {
         FieldOfView& setBounds(glm::vec3 const& low, glm::vec3 const& high) {
                 _vecBoundsLow = low; _vecBoundsHigh = high; return *this; }
 
-        FieldOfView& setOrientation(glm::mat4 const& matrix) { _matOrientation = matrix; return *this; }
+        FieldOfView& setView(glm::mat4 const& matrix) { _matView = matrix; return *this; }
+
+        FieldOfView& setOrientation(glm::mat4 const& matrix);
 
         FieldOfView& setPerspective(float angle) { _valAngle = angle; return *this; }
 
@@ -52,13 +62,20 @@ class FieldOfView {
 
         // dumb accessors
 
-        glm::mat4 const& getOrientation()    const   { return _matOrientation; }
+        glm::mat4 const& getView()           const   { return _matView; }
         float            getWidthInPixels()  const   { return _valWidth; }
         float            getHeightInPixels() const   { return _valHeight; }
         float            getPerspective()    const   { return _valAngle; }
 
         // matrices
 
+        //
+        // Returns a matrix representing the camera position and rotation in
+        // space. Similar to getViewerWorldXform but without translation offset
+        // applied.
+        //
+        glm::mat4 getOrientation() const;
+
         // 
         // Returns a full transformation matrix to project world coordinates
         // onto the screen.
@@ -100,7 +117,8 @@ class FieldOfView {
         float getPixelSize() const;
 
         // 
-        // Returns the frustum as used for the projection matrices.
+        // Returns the frustum as used for the projection matrices. That
+        // is the one that applies when the current orientation is at identity.
         // The result depdends on the bounds, eventually aspect correction
         // for the current resolution, the perspective angle (specified in
         // respect to diagonal) and zoom.
@@ -109,7 +127,8 @@ class FieldOfView {
 
         // 
         // Returns the z-offset from the origin to where orientation ia
-        // applied.
+        // applied (in negated form equivalent to the 'near' parameter of
+        // gluPerspective).
         // 
         float getTransformOffset() const { return _vecBoundsHigh.z; }
 
@@ -119,5 +138,5 @@ class FieldOfView {
         float getAspectRatio() const { return _valHeight / _valWidth; }
 };
 
-#endif
+#endif /* defined(__hifi__FieldOfView__) */