Simplified and improved the glyph margin computation and usage

examples/osgfont/osgfont.cpp

@@ -68,9 +68,6 @@ struct TextSettings
         minFilter(osg::Texture::LINEAR_MIPMAP_LINEAR),
         magFilter(osg::Texture::LINEAR),
         maxAnisotropy(16.0f),
-        glyphImageMargin(1),
-        glyphImageMarginRatio(0.02),
-        glyphInterval(1),
         glyphTextureFeatures(osgText::GlyphTexture::GREYSCALE),
         textColor(1.0f, 1.0f, 1.0f, 1.0f),
         backdropType(osgText::Text::NONE),
@@ -118,10 +115,6 @@ struct TextSettings
 
         if (arguments.read("--anisotropy",maxAnisotropy)) {}
 
-        if (arguments.read("--margin", glyphImageMargin)) {}
-        if (arguments.read("--margin-ratio", glyphImageMarginRatio)) {}
-        if (arguments.read("--interval", glyphInterval)) {}
-
 
         if (arguments.read("--outline")) backdropType = osgText::Text::OUTLINE;
         if (arguments.read("--shadow")) backdropType = osgText::Text::DROP_SHADOW_BOTTOM_RIGHT;
@@ -158,12 +151,9 @@ struct TextSettings
 
         if (!font) font = osgText::Font::getDefaultFont();
 
-        font->setGlyphImageMargin(glyphImageMargin);
-        font->setGlyphImageMarginRatio(glyphImageMarginRatio);
         font->setMinFilterHint(minFilter);
         font->setMagFilterHint(magFilter);
         font->setMaxAnisotropy(maxAnisotropy);
-        font->setGlyphInterval(glyphInterval);
         font->setGyphTextureFeatures(glyphTextureFeatures);
 
         text.setColor(textColor);
@@ -184,9 +174,6 @@ struct TextSettings
     osg::Texture::FilterMode        minFilter;
     osg::Texture::FilterMode        magFilter;
     float                           maxAnisotropy;
-    unsigned int                    glyphImageMargin;
-    float                           glyphImageMarginRatio;
-    int                             glyphInterval;
     osgText::GlyphTexture::Features glyphTextureFeatures;
 
     osg::Vec4                       textColor;
@@ -204,22 +191,18 @@ osgText::Text* createLabel(const std::string& l, TextSettings& settings, unsigne
 
     settings.setText(*label);
 
-
     if (settings.scaleFontSizeToFontResolution)
     {
         label->setCharacterSize(size);
     }
 
-
     label->setFontResolution(size, size);
     label->setPosition(pos);
     label->setAlignment(osgText::Text::LEFT_BOTTOM);
 
-
     // It seems to be important we do this last to get best results?
     label->setText(l);
 
-
     // textInfo(label);
 
     pos.y() += label->getCharacterHeight()*2.0;

include/osgText/Font

@@ -107,23 +107,6 @@ public:
      *  return true on success, return false when not supported.*/
     virtual bool getVerticalSize(float& ascender, float& descender) const { return _implementation ? _implementation->getVerticalSize(ascender, descender) : false; }
 
-    /** Set the margin around each glyph,
-      * to ensure that texture filtering doesn't bleed adjacent glyph's into each other.
-      * Default margin is 1 texels.*/
-    void setGlyphImageMargin(unsigned int margin);
-    unsigned int getGlyphImageMargin() const;
-
-    /** Set the margin ratio around each glyph, relative to the glyph's size.
-      * to ensure that texture filtering doesn't bleed adjacent glyph's into each other.
-      * Default margin is 0.05.*/
-    void setGlyphImageMarginRatio(float margin);
-    float getGlyphImageMarginRatio() const;
-
-    /** Set the interval that glyph positions are clamped to.
-      * Default interval is 1 texels.*/
-    void setGlyphInterval(int interval);
-    int getGlyphInterval() const;
-
 
     void setGyphTextureFeatures(GlyphTexture::Features features) { _glyphTextureFeatures = features; }
     GlyphTexture::Features getGlyphTextureFeatures() const { return _glyphTextureFeatures; }
@@ -202,9 +185,7 @@ protected:
 
     // current active size of font
     FontResolution                  _fontSize;
-    unsigned int                    _margin;
+
-    float                           _marginRatio;
-    int                             _glyphInterval;
     GlyphTexture::Features          _glyphTextureFeatures;
 
     unsigned int                    _textureWidthHint;

include/osgText/Glyph

@@ -93,6 +93,9 @@ public:
     void setMaxTexCoord(const osg::Vec2& coord);
     const osg::Vec2& getMaxTexCoord() const;
 
+    void setTexelMargin(float margin) { _texelMargin = margin; }
+    float getTexelMargin() const { return _texelMargin; }
+
 protected:
 
     virtual ~Glyph();
@@ -116,6 +119,7 @@ protected:
     int                         _texturePosY;
     osg::Vec2                   _minTexCoord;
     osg::Vec2                   _maxTexCoord;
+    float                       _texelMargin;
 
     typedef osg::buffered_value<GLuint> GLObjectList;
     mutable GLObjectList _globjList;
@@ -256,16 +260,6 @@ public:
     /** return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs.*/
     virtual int compare(const osg::StateAttribute& rhs) const;
 
-    /** Set the margin around each glyph, to ensure that texture filtering doesn't bleed adjacent glyph's into each other.*/
-    void setGlyphImageMargin(unsigned int margin) { _margin = margin; }
-    unsigned int getGlyphImageMargin() const { return _margin; }
-
-    void setGlyphImageMarginRatio(float margin) { _marginRatio = margin; }
-    float getGlyphImageMarginRatio() const { return _marginRatio; }
-
-    void setGlyphInterval(int interval) { _interval = interval; }
-    int getGlyphInterval() const { return _interval; }
-
     enum Features
     {
         GREYSCALE,
@@ -277,6 +271,10 @@ public:
     void setGlyphTextureFeatures(Features features) { _glyphTextureFeatures = features; }
     Features getGlyphTextureFeatures() const { return _glyphTextureFeatures; }
 
+
+    int getEffectMargin(const Glyph* glyph);
+    int getTexelMargin(const Glyph* glyph);
+
     bool getSpaceForGlyph(Glyph* glyph, int& posX, int& posY);
 
     void addGlyph(Glyph* glyph,int posX, int posY);
@@ -296,12 +294,6 @@ protected:
 
     void copyGlyphImage(Glyph* glyph);
 
-
-    // parameter used to compute the size and position of empty space
-    // in the texture which could accommodate new glyphs.
-    int         _margin;
-    float       _marginRatio;
-    int         _interval;
     Features    _glyphTextureFeatures;
 
     int         _usedY;

src/osgPlugins/freetype/FreeTypeFont.cpp

@@ -278,19 +278,6 @@ void FreeTypeFont::setFontResolution(const osgText::FontResolution& fontSize)
 
     int width = fontSize.first;
     int height = fontSize.second;
-    int maxAxis = std::max(width, height);
-    int margin = _facade->getGlyphImageMargin() + (int)((float)maxAxis * _facade->getGlyphImageMarginRatio());
-
-    if ((unsigned int)(width+2*margin) > _facade->getTextureWidthHint() ||
-        (unsigned int)(width+2*margin) > _facade->getTextureHeightHint())
-    {
-        OSG_WARN<<"Warning: FreeTypeFont::setSize("<<width<<","<<height<<") sizes too large,"<<std::endl;
-
-        width = _facade->getTextureWidthHint()-2*margin;
-        height = _facade->getTextureHeightHint()-2*margin;
-
-        OSG_WARN<<"         sizes capped ("<<width<<","<<height<<") to fit int current glyph texture size."<<std::endl;
-    }
 
     FT_Error error = FT_Set_Pixel_Sizes( _face,      /* handle to face object  */
                                          width,      /* pixel_width            */

src/osgText/DefaultFont.cpp

@@ -29,9 +29,6 @@ DefaultFont::DefaultFont()
     _minFilterHint = osg::Texture::LINEAR_MIPMAP_LINEAR;
     _magFilterHint = osg::Texture::NEAREST;
 
-    _margin = 8;
-    _marginRatio = 0.0;
-    _glyphInterval = 16;
 
     constructGlyphs();
 }

src/osgText/Font.cpp

@@ -224,9 +224,6 @@ osg::ref_ptr<Font> osgText::readRefFontStream(std::istream& stream, const osgDB:
 
 Font::Font(FontImplementation* implementation):
     osg::Object(true),
-    _margin(1),
-    _marginRatio(0.02),
-    _glyphInterval(1),
 #if 0
     _glyphTextureFeatures(GlyphTexture::ALL_FEATURES),
 #else
@@ -289,32 +286,6 @@ std::string Font::getFileName() const
     return std::string();
 }
 
-void Font::setGlyphImageMargin(unsigned int margin)
-{
-    _margin = margin;
-}
-
-unsigned int Font::getGlyphImageMargin() const
-{
-    return _margin;
-}
-
-void Font::setGlyphImageMarginRatio(float ratio)
-{
-    _marginRatio = ratio;
-}
-
-float Font::getGlyphImageMarginRatio() const
-{
-    return _marginRatio;
-}
-
-void Font::setGlyphInterval(int interval)
-{
-    _glyphInterval = interval;
-}
-
-
 void Font::setTextureSizeHint(unsigned int width,unsigned int height)
 {
     _textureWidthHint = width;
@@ -514,9 +485,6 @@ void Font::addGlyph(const FontResolution& fontRes, unsigned int charcode, Glyph*
         OSG_INFO<< "   Font " << this<< ", numberOfTexturesAllocated "<<numberOfTexturesAllocated<<std::endl;
 
         // reserve enough space for the glyphs.
-        glyphTexture->setGlyphImageMargin(_margin);
-        glyphTexture->setGlyphImageMarginRatio(_marginRatio);
-        glyphTexture->setGlyphInterval(_glyphInterval);
         glyphTexture->setGlyphTextureFeatures(_glyphTextureFeatures);
         glyphTexture->setTextureSize(_textureWidthHint,_textureHeightHint);
         glyphTexture->setFilter(osg::Texture::MIN_FILTER,_minFilterHint);

src/osgText/Glyph.cpp

@@ -37,9 +37,6 @@ using namespace std;
 #endif
 
 GlyphTexture::GlyphTexture():
-    _margin(1),
-    _marginRatio(0.02f),
-    _interval(1),
     _usedY(0),
     _partUsedX(0),
     _partUsedY(0)
@@ -60,21 +57,39 @@ int GlyphTexture::compare(const osg::StateAttribute& rhs) const
     return 0;
 }
 
+int GlyphTexture::getEffectMargin(const Glyph* glyph)
+{
+    if (_glyphTextureFeatures==GREYSCALE) return 0;
+    else return glyph->getFontResolution().second/4;
+}
+
+int GlyphTexture::getTexelMargin(const Glyph* glyph)
+{
+    int width = glyph->s();
+    int height = glyph->t();
+    int effect_margin = getEffectMargin(glyph);
+
+    int max_dimension = std::max(width, height) + 2 * effect_margin;
+    int margin = osg::maximum(max_dimension/4, 2) + effect_margin;
+
+    return margin;
+}
 
 bool GlyphTexture::getSpaceForGlyph(Glyph* glyph, int& posX, int& posY)
 {
-    int maxAxis = osg::maximum(glyph->s(), glyph->t());
+    int width = glyph->s();
-    int margin_from_ratio = (int)((float)maxAxis * _marginRatio);
+    int height = glyph->t();
-    int search_distance = glyph->getFontResolution().second/8;
 
-    int margin = _margin + osg::maximum(margin_from_ratio, search_distance);
+    int margin = getTexelMargin(glyph);
 
-    int width = glyph->s()+2*margin;
+    width += 2*margin;
-    int height = glyph->t()+2*margin;
+    height += 2*margin;
 
-    int partUsedX = ((_partUsedX % _interval) == 0) ? _partUsedX : (((_partUsedX/_interval)+1)*_interval);
+    int interval = 4;
-    int partUsedY = ((_partUsedY % _interval) == 0) ? _partUsedY : (((_partUsedY/_interval)+1)*_interval);
+
-    int usedY = ((_usedY % _interval) == 0) ? _usedY : (((_usedY/_interval)+1)*_interval);
+    int partUsedX = ((_partUsedX % interval) == 0) ? _partUsedX : (((_partUsedX/interval)+1)*interval);
+    int partUsedY = ((_partUsedY % interval) == 0) ? _partUsedY : (((_partUsedY/interval)+1)*interval);
+    int usedY = ((_usedY % interval) == 0) ? _usedY : (((_usedY/interval)+1)*interval);
 
     // first check box (partUsedX, usedY) to (width,height)
     if (width <= (getTextureWidth()-partUsedX) &&
@@ -132,6 +147,9 @@ void GlyphTexture::addGlyph(Glyph* glyph, int posX, int posY)
     glyph->setMaxTexCoord( osg::Vec2( static_cast<float>(posX+glyph->s())/static_cast<float>(getTextureWidth()),
                                       static_cast<float>(posY+glyph->t())/static_cast<float>(getTextureHeight()) ) );
 
+
+    glyph->setTexelMargin(float(getTexelMargin(glyph)));
+
     copyGlyphImage(glyph);
 }
 
@@ -156,7 +174,7 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
     int dest_rows = _image->t();
     unsigned char* dest_data = _image->data(glyph->getTexturePositionX(),glyph->getTexturePositionY());
 
-    int search_distance = glyph->getFontResolution().second/4;
+    int search_distance = getEffectMargin(glyph);
 
     int left = -search_distance;
     int right = glyph->s()+search_distance;

src/osgText/Text.cpp

@@ -464,8 +464,6 @@ void Text::computeGlyphRepresentation()
     float hr = _characterHeight;
     float wr = hr/getCharacterAspectRatio();
 
-    float texelMargin = 5.0f;
-
     for(String::iterator itr=_text.begin();
         itr!=_text.end();
         )
@@ -632,6 +630,7 @@ void Text::computeGlyphRepresentation()
                     osg::Vec2 mintc = glyph->getMinTexCoord();
                     osg::Vec2 maxtc = glyph->getMaxTexCoord();
                     osg::Vec2 vDiff = maxtc - mintc;
+                    float texelMargin = glyph->getTexelMargin();
 
                     float fHorizTCMargin = texelMargin / glyph->getTexture()->getTextureWidth();
                     float fVertTCMargin = texelMargin / glyph->getTexture()->getTextureHeight();