=> R0 = flags b0 = R2 is a sprite address, not a name
b1 = R4 is a sprite address, not a name
b2 = lock the table after creation
R1 = source mode or sprite area
R2 = source palette or sprite
R3 = destination mode or sprite area
R4 = destination palette or sprite
R5 = translucency 0-256
R6 = buffer
<= R0 = number of colours in source
R1 = number of colours in destination
R2 = size of buffer
R6 = pointer to table if locking requested, else preserved
This computes a lookup table to allow for the efficient blending of colours between a source and destination palette for a given level of transparency.
The register pairs R1/R2 and R3/R4 accept the same combinations that ColourTrans_ReadPalette does.
The value in R5 is used to select proportions of two palette entries using the following equation
index = ((src * (256 - R5)) + (dst * R5)) / 256
from which it can be seen that R5=0 gives a completely opaque source, and R5=256 is a completely transparent source.
On entry the buffer in R6 can be 0 to determine the size, or a private buffer to return the table into (having found its size first), or is ignored when R0 b2 is set. For locked tables, BlendTable will allocate a buffer for you which you must later release.
The table returned can be indexed by
index = table ? (src + (dst * number_of_colours_in_source))
to find the palette index post blending.
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