Implement "player color palettes"

[franciscod]

I don't think age2 used fancy shaders for coloring... so... from http://steamcommunity.com/sharedfiles/filedetails/?id=190070326:

"The player color means which color you used in your bmp as player color. This is important as the AoE palette has 8 exactly defined values for every players color shades. When extracting a bmp, every pixel that is supposed to change it's color according to players color will be colored in the chosen player color (default is blue). To convert a real color back to the undefined player color one, you have to set this. If you choose red for example, no red pixel - even if it matches a red player color value - will be interpreted as player color but shown as red - for every player.

On the other hand, every pixel that changed to a color shade of the chosen player color while converting - even if it wasn't meant to have players color - will have it ingame. And every pixel supposed to have the players color but doesn't have the right color value after converting - will not change its color ingame."

[franciscod]

...or is this already done via shaders? are we keeping the shaders?

[zuntrax]

The parts of the texture that should have player colors are marked with an alpha value of 254 or 253 (I think the other one was for outlines). When rendering, a shader replaces these areas with the given player color. Edit: I don't see a reason not to keep this implementation.

[mic-e]

The original age2 renderer used direct draw and SLP files as drawing instructions. Each time it would render a unit it would read the SLP file, which would e.g. say "draw a line with the playercolor from (10,20) to (23, 5)".

IIRC, openage.convert

• reads the color palette and puts it in some docx file (don't remember which one)
• represents player-colored parts in the PNG as an alpha value, as mentioned by @zuntrax

The engine has a shader that takes the color palette and player id and replaces all marked pixels by the player's color.

Alternatively, one could just create 8 PNG files (one for each player), but that would take 8 times the memory (on the filesystem, in RAM, and in the graphics memory) and would severely limit our ability to introduce new player colors.

[TheJJ]

The palette is placed in $conversiondir/player_palette_50500.docx. You can adjust the color values there, the conversion is done in py/openage/convert/colortable.py.