From 7f97b9f999e48a5766de8820f83e594ae45a4641 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Tue, 21 Nov 2017 13:41:57 +0000
Subject: [PATCH] Added Text::getCharacterCorners(...) method to help
 applications that want to find out the positions of characters being
 rendered.

---
 include/osgText/Text     |  4 ++++
 include/osgText/TextBase |  8 ++++----
 src/osgText/Text.cpp     | 15 +++++++++++++++
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/include/osgText/Text b/include/osgText/Text
index ab5e547a0..2bd443f19 100644
--- a/include/osgText/Text
+++ b/include/osgText/Text
@@ -182,9 +182,13 @@ public:
     virtual void accept(osg::PrimitiveFunctor& pf) const;
 
 
+    /** Get the coordinates of the character corners in local coordinates. Use Text::getMatrix() or Text::computeMatrix(..) to get the transform into model coordinates (see TextBase header.) */
+    bool getCharacterCorners(unsigned int index, osg::Vec3& bottomLeft, osg::Vec3& bottomRight, osg::Vec3& topLef, osg::Vec3& topRight) const;
+
     /** Resize any per context GLObject buffers to specified size. */
     virtual void resizeGLObjectBuffers(unsigned int maxSize);
 
+
     /** If State is non-zero, this function releases OpenGL objects for
       * the specified graphics context. Otherwise, releases OpenGL objexts
       * for all graphics contexts. */
diff --git a/include/osgText/TextBase b/include/osgText/TextBase
index d75e41ff2..f262a0593 100644
--- a/include/osgText/TextBase
+++ b/include/osgText/TextBase
@@ -279,10 +279,12 @@ public:
     void getCoord(unsigned int i, osg::Vec2& c) const { c.set((*_coords)[i].x(), (*_coords)[i].y()); }
     void getCoord(unsigned int i, osg::Vec3& c) const { c = (*_coords)[i]; }
 
-
-    /** Get the internal matrix used to provide positioning of text.*/
+    /** Get the cached internal matrix used to provide positioning of text.  The cached matrix is originally computed by computeMatrix(..). */
     const osg::Matrix& getMatrix() const { return _matrix; }
 
+    /** compute the matrix that positions the text in model space for the given viewpoint.*/
+    bool computeMatrix(osg::Matrix& matrix, osg::State* state=0) const;
+
 protected:
 
     virtual ~TextBase();
@@ -295,8 +297,6 @@ protected:
 
     osg::VertexArrayState* createVertexArrayState(osg::RenderInfo& renderInfo) const;
 
-    bool computeMatrix(osg::Matrix& matrix, osg::State* state=0) const;
-
     void positionCursor(const osg::Vec2 & endOfLine_coords, osg::Vec2 & cursor, unsigned int linelength);
     String::iterator computeLastCharacterOnLine(osg::Vec2& cursor, String::iterator first,String::iterator last);
     void computePositions();
diff --git a/src/osgText/Text.cpp b/src/osgText/Text.cpp
index a22d7396f..6a2d2f96c 100644
--- a/src/osgText/Text.cpp
+++ b/src/osgText/Text.cpp
@@ -1301,6 +1301,21 @@ void Text::accept(osg::PrimitiveFunctor& pf) const
     }
 }
 
+bool Text::getCharacterCorners(unsigned int index, osg::Vec3& bottomLeft, osg::Vec3& bottomRight, osg::Vec3& topLeft, osg::Vec3& topRight) const
+{
+    if (_coords) return false;
+
+    if ((index*4+4)>static_cast<unsigned int>(_coords->size())) return false;
+
+    unsigned int base = index*4;
+    topLeft = (*_coords)[base];
+    bottomLeft = (*_coords)[base+1];
+    bottomRight = (*_coords)[base+2];
+    topRight = (*_coords)[base+3];
+
+    return true;
+}
+
 void Text::resizeGLObjectBuffers(unsigned int maxSize)
 {
     TextBase::resizeGLObjectBuffers(maxSize);