Multi-texturing March 2, 2009 cliffski Part of today was spent on the fleet design screen adding pilots as a requirement. This is something I’ve got from the old travller game. Basically some missions will have a limited number of trained pilots for your ships, thus limiting the number of small fighters that are viable for your fleet. I also finalised which space backgrounds would go with each mission. Then it was on to some graphical stuff… I’ve added a new weapon, which is an ECM blaster that knocks out the targeting systems of a ship for a few seconds. Ideally you would have a ship that acted as ECM cruiser to knock out the weapons of the enemy cruisers before you sent in your fighters and bombers to blast them to bits :D. As a result, I need a graphical effect on the target ship to show its been zapped. The existing shield effect isn’t the same sort of thing, because it’s a seperate sprite drawn on top which surrounds the ship in a sphere. I needed something that ‘hugged’ the outline of the target ship. In a 3D game, you would maybe have an animated texture which you applied to the ships mesh, but these ships are sprites so that won’t work. The solution has been to layer two textures together and render them in one pass. Basically, I have a generic ‘lightning effect’ texture which is drawn on top of the ship, but I tell directx to use the alpha channel from the ships sprite as the alpha, and the color data from the lightning to draw the effect. That bit was a pain to get right, but once done, I then needed to animate it. That is being done by having two lots of texture coordinates for the effect sprite. I leave the first set (for the ship, used as the alpha mask) at their defaults, and the effect color layer uses the second set. That lets me ‘ripple’, scroll or shake the effect texture, and still have it ‘wrap’ closely around the outline of the ship. It works, but I need to program a decent movement effect, and do a proper effect texture. Then I’ll post screens :D.