draw_set_alpha_test_ref_value(value);
| Argument | Description |
|---|---|
| value | Sets the reference value for alpha testing from 0 to 255 (default value is 0) |
Returns: N/A
This function will set the reference value for the alpha testing
(when it has been enabled using the draw_set_alpha_test). This
is the "cut-off" threshold at which pixels with alpha will not be
drawn.
Basically, if you have this value set to 0 and you have texture interpolation
turned on, you can still get visual errors at the edges of
overlapping objects. This is because you can have almost
completely transparent areas that block things drawn behind them,
but if you set this reference value to, for example, 254 (i.e. one
below maximum), this guarantees that only 100% opaque pixels are
going to be drawn. You can also turn texture interpolation off,
which would normally allow you to use the default values with no
problems and no need to use this function at all, however a lot
depends on the source artwork.
NOTE: This is an advanced drawing feature, so if you are
not sure whether you need it or not, or don't know exactly what it
does, you are probably better off not using it as it can seriously
corrupt how your game is drawn.
draw_set_alpha_test(true);
draw_set_alpha_test_ref_value(128);
The above code will switch on alpha testing and set the test threshold to 128 (only pixels with an alpha over 0.5 will be drawn).