I am using freetype library (from www.freetype.org)) to display freetype fonts. I want to apply RGBA texture image to the font. How to apply the RGBA texture image to the font? Here I am giving some code from freetype library. Please check the code and give response if is there any possibilty to apply texture to the font.
FTGlyph* FTGLTextureFont::MakeGlyph( unsigned int glyphIndex)
{
FT_Glyph* ftGlyph = face.Glyph( glyphIndex, FT_LOAD_NO_HINTING);
if( ftGlyph)
{
glyphHeight = static_cast<int>( charSize.Height());
glyphWidth = static_cast<int>( charSize.Width());
if( numTextures == 0)
{
glTextureID[0] = [b]CreateTexture()[/b];
xOffset = yOffset = padding;
++numTextures;
}
if( xOffset > ( textureWidth - glyphWidth))
{
xOffset = padding;
yOffset += glyphHeight;
if( yOffset > ( textureHeight - glyphHeight))
{
glTextureID[numTextures] = [b]CreateTexture()[/b];
++numTextures;
yOffset = padding;
}
}
FTTextureGlyph* tempGlyph = new FTTextureGlyph( *ftGlyph, glTextureID[numTextures - 1],
xOffset, yOffset, textureWidth, textureHeight);
xOffset += static_cast<int>( tempGlyph->BBox().upperX - tempGlyph->BBox().lowerX + padding);
--remGlyphs;
return tempGlyph;
}
err = face.Error();
return NULL;
}
void FTGLTextureFont::CalculateTextureSize()
{
if( !maxTextSize)
{
glGetIntegerv( GL_MAX_TEXTURE_SIZE, (GLint*)&maxTextSize);
}
textureWidth = NextPowerOf2( (remGlyphs * glyphWidth) + ( padding * 2));
if( textureWidth > maxTextSize)
{
textureWidth = maxTextSize;
}
int h = static_cast<int>( (textureWidth - ( padding * 2)) / glyphWidth);
textureHeight = NextPowerOf2( (( numGlyphs / h) + 1) * glyphHeight);
textureHeight = textureHeight > maxTextSize ? maxTextSize : textureHeight;
}
GLuint FTGLTextureFont::CreateTexture()
{
CalculateTextureSize();
int totalMemory = textureWidth * textureHeight;
unsigned char* textureMemory = new unsigned char[totalMemory];
memset( textureMemory, 0, totalMemory);
GLuint textID;
glGenTextures( 1, (GLuint*)&textID);
glBindTexture( GL_TEXTURE_2D, textID);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D( GL_TEXTURE_2D, 0, GL_ALPHA, textureWidth, textureHeight, 0, GL_ALPHA, GL_UNSIGNED_BYTE, textureMemory);
delete [] textureMemory;
return textID;
}
And here is another class methods:
FTTextureGlyph::FTTextureGlyph( FT_Glyph glyph, int id, int xOffset, int yOffset, GLsizei width, GLsizei height)
: FTGlyph( glyph),
destWidth(0),
destHeight(0),
glTextureID(id),
activeTextureID(0)
{
err = FT_Glyph_To_Bitmap( &glyph, FT_RENDER_MODE_NORMAL, 0, 1);
if( err | | glyph->format != ft_glyph_format_bitmap)
{
return;
}
FT_BitmapGlyph bitmap = ( FT_BitmapGlyph)glyph;
FT_Bitmap* source = &bitmap->bitmap;
destWidth = source->width;
destHeight = source->rows;
//
if( destWidth && destHeight)
{
glPushClientAttrib( GL_CLIENT_PIXEL_STORE_BIT);
glPixelStorei( GL_UNPACK_LSB_FIRST, GL_FALSE);
glPixelStorei( GL_UNPACK_ROW_LENGTH, 0);
glPixelStorei( GL_UNPACK_ALIGNMENT, 1);
glBindTexture( GL_TEXTURE_2D, glTextureID);
glTexSubImage2D( GL_TEXTURE_2D, 0, xOffset, yOffset, destWidth, destHeight, GL_ALPHA, GL_UNSIGNED_BYTE, source->buffer);
glPopClientAttrib();
}
// 0
// ±—+
// | |
// | |
// | |
// ±—+
// 1
uv[0].x = static_cast<float>(xOffset) / static_cast<float>(width);
uv[0].y = static_cast<float>(yOffset) / static_cast<float>(height);
uv[1].x = static_cast<float>( xOffset + destWidth) / static_cast<float>(width);
uv[1].y = static_cast<float>( yOffset + destHeight) / static_cast<float>(height);
pos.x = bitmap->left;
pos.y = bitmap->top;
FT_Done_Glyph( glyph);
}
float FTTextureGlyph::Render( const FTPoint& pen)
{
glGetIntegerv( GL_TEXTURE_2D_BINDING_EXT, &activeTextureID);
if( activeTextureID != glTextureID)
{
glBindTexture( GL_TEXTURE_2D, (GLuint)glTextureID);
}
glBegin( GL_QUADS);
glTexCoord2f( uv[0].x, uv[0].y);
glVertex2f( pen.x + pos.x, pen.y + pos.y);
glTexCoord2f( uv[0].x, uv[1].y);
glVertex2f( pen.x + pos.x, pen.y + pos.y - destHeight);
glTexCoord2f( uv[1].x, uv[1].y);
glVertex2f( pen.x + destWidth + pos.x, pen.y + pos.y - destHeight);
glTexCoord2f( uv[1].x, uv[0].y);
glVertex2f( pen.x + destWidth + pos.x, pen.y + pos.y);
glEnd();
return advance;
}
[This message has been edited by ramana (edited 12-17-2003).]