Game Development Reference
In-Depth Information
The Font Class
We are going to use bitmap fonts to render arbitrary (ASCII) text. We already discussed how this
works on a high level, so let's look at the code in Listing 9-4.
Listing 9-4. Font.java, a Bitmap Font-Rendering Class
package
com.badlogic.androidgames.framework.gl;
public class
Font {
public final
Texture texture;
public final int
glyphWidth;
public final int
glyphHeight;
public final
TextureRegion[] glyphs =
new
TextureRegion[96];
The class stores the texture containing the font's glyph, the width and height of a single glyph,
and an array of
TextureRegions
—one for each glyph. The first element in the array holds the
region for the space glyph, the next one holds the region for the exclamation mark glyph, and so
on. In other words, the first element corresponds to the ASCII character with the code 32, and
the last element corresponds to the ASCII character with the code 126.
public
Font(Texture texture,
int
offsetX,
int
offsetY,
int
glyphsPerRow,
int
glyphWidth,
int
glyphHeight) {
this
.texture = texture;
this
.glyphWidth = glyphWidth;
this
.glyphHeight = glyphHeight;
int
x = offsetX;
int
y = offsetY;
for
(
int
i = 0; i < 96; i++) {
glyphs[i] =
new
TextureRegion(texture, x, y, glyphWidth, glyphHeight);
x += glyphWidth;
if
if(x == offsetX + glyphsPerRow * glyphWidth) {
x = offsetX;
y += glyphHeight;
}
}
}
In the constructor, we store the configuration of the bitmap font and generate the glyph
regions. The
offsetX
and
offsetY
parameters specify the top-left corner of the bitmap font
area in the texture. In our texture atlas, that's the pixel at (224,0). The parameter
glyphsPerRow
tells us how many glyphs there are per row, and the parameters
glyphWidth
and
glyphHeight
specify the size of a single glyph. Since we use a fixed-width bitmap font, that size is the
same for all glyphs. The
glyphWidth
is also the value by which we will advance when rendering
multiple glyphs.
public void
drawText(SpriteBatcher batcher, String text,
float
x,
float
y) {
int
len = text.length();
for
(
int
i = 0; i < len; i++) {
