/// <summary>
/// Sets up a single character as a OpenGL texture for rendering.
/// </summary>
/// <param name="face"></param>
/// <param name="faceptr"></param>
/// <param name="c"></param>
private void CompileCharacter(Face face, IntPtr faceptr, int c)
{
//We first convert the number index to a character index
int index = Face.FT_Get_Char_Index(faceptr, Convert.ToChar(c));
//Here we load the actual glyph for the character
int ret = Face.FT_Load_Glyph(faceptr, index, FT_LOAD_TYPES.FT_LOAD_DEFAULT);
if (ret != 0)
{
return;
}
//Convert the glyph to a bitmap
IntPtr glyph;
int retb = Glyph.FT_Get_Glyph(face.glyphrec, out glyph);
if (retb != 0)
{
return;
}
// Render the glphy to a bitmap
Glyph.FT_Glyph_To_Bitmap(out glyph, FT_RENDER_MODES.FT_RENDER_MODE_NORMAL, 0, 1);
BitmapGlyph glyph_bmp = (BitmapGlyph)Marshal.PtrToStructure(glyph, typeof(BitmapGlyph));
int size = (glyph_bmp.bitmap.width * glyph_bmp.bitmap.rows);
if (size <= 0)
{
//space is a special `blank` character
extent_x[c] = 0;
if (c == 32)
{
Gl.glNewList((int)(list_base + c), Gl.GL_COMPILE);
Gl.glTranslatef(fontSize >> 1, 0, 0);
extent_x[c] = fontSize >> 1;
Gl.glEndList();
}
return;
}
// Allocate space and grab the bitmap
byte[] bmp = new byte[size];
Marshal.Copy(glyph_bmp.bitmap.buffer, bmp, 0, bmp.Length);
// Save the size of the bitmap and create a power of 2 version
// for OpenGL.
glyphSizes[c] =
new SizeF(glyph_bmp.bitmap.width,
glyph_bmp.bitmap.rows);
baselines[c] = glyph_bmp.top - glyph_bmp.bitmap.rows;
int width = next_po2(glyph_bmp.bitmap.width);
int height = next_po2(glyph_bmp.bitmap.rows);
byte[] expanded = new byte[2 * width * height];
for (int j = 0; j < height; j++)
{
for (int i = 0; i < width; i++)
{
expanded[2 * (i + j * width)] = expanded[2 * (i + j * width) + 1] =
(i >= glyph_bmp.bitmap.width || j >= glyph_bmp.bitmap.rows) ?
(byte)0 : bmp[i + glyph_bmp.bitmap.width * j];
}
}
// Set up some texture parameters for opengl
Gl.glBindTexture(Gl.GL_TEXTURE_2D, textures[c]);
Gl.glTexParameteri(Gl.GL_TEXTURE_2D, Gl.GL_TEXTURE_MAG_FILTER, Gl.GL_LINEAR);
Gl.glTexParameteri(Gl.GL_TEXTURE_2D, Gl.GL_TEXTURE_MIN_FILTER, Gl.GL_LINEAR);
// Create the texture
Gl.glTexImage2D(Gl.GL_TEXTURE_2D, 0, Gl.GL_RGBA, width, height,
0, Gl.GL_LUMINANCE_ALPHA, Gl.GL_UNSIGNED_BYTE, expanded);
expanded = null;
bmp = null;
// Create a display list and bind a texture to it
Gl.glNewList((int)(list_base + c), Gl.GL_COMPILE);
Gl.glBindTexture(Gl.GL_TEXTURE_2D, textures[c]);
//Account for freetype spacing rules
Gl.glTranslatef(glyph_bmp.left, 0, 0);
Gl.glPushMatrix();
//Gl.glRotatef(180, 1f, 0, 0);
Gl.glScalef(1, -1, 1);
Gl.glTranslatef(0, glyph_bmp.top - glyph_bmp.bitmap.rows, 0);
float x = (float)glyph_bmp.bitmap.width / (float)width;
float y = (float)glyph_bmp.bitmap.rows / (float)height;
//Draw the quad
Gl.glBegin(Gl.GL_QUADS);
{
Gl.glTexCoord2d(0, 0);
Gl.glVertex2f(0, glyph_bmp.bitmap.rows);
Gl.glTexCoord2d(0, y);
Gl.glVertex2f(0, 0);
Gl.glTexCoord2d(x, y);
Gl.glVertex2f(glyph_bmp.bitmap.width, 0);
Gl.glTexCoord2d(x, 0);
Gl.glVertex2f(glyph_bmp.bitmap.width, glyph_bmp.bitmap.rows);
}
Gl.glEnd();
Gl.glPopMatrix();
// Advance for the next character
Gl.glTranslatef(glyph_bmp.bitmap.width, 0, 0);
extent_x[c] = glyph_bmp.left + glyph_bmp.bitmap.width;
Gl.glEndList();
}
