GCOL is used to select the logical colours used by graphics statements.
|Availability||Present in all original versions of BBC BASIC.|
|Syntax||BASIC I-IV|| |
|BASIC V|| |
|Token (hex)||BASIC I-V|| |
|Description||BASIC I-V|| If bit 7 of the second <numeric> is 0
If bit 7 of the second <numeric> is 1 then
The current contents of the screen are not affected.
In BASIC V the
|Associated keywords|| |
This statement sets the colour to be used by all subsequent graphics operations. It can set the foreground and background graphics colours. It also specifies how the colour is to be placed on the screen.
The first number specifies the mode of action.
0 plot the specified colour
1 OR the colour with the colour already there
2 AND the colour with the colour already there
3 Exclusive-OR the colour with the colour already there
4 invert the colour already there.
The GXR and Master added 16*n+k for n=1-4. Arthur added actions 5-7, 8-15, and 16*n+k with n=5.
The second number specifies the logical colour. If the number is less than 128 then it defines the graphics foreground colour. If the number is greater than 127 then it defines the graphics background colour.
In the two-argument form it is simply a veneer for