This technique can be used to make any blood generated when a creature is shot form a small blood pool on the ground rather than disappearing. Usually this is done simply by sing one of the smaller blood pools that exist already in the game, but I will use a small wad file with extra graphics to illustrate another aspect of dehacking.
Step 1. We are going to use new graphics added on to the end of an existing graphic sequence. In this case, the blood splat sequence. This sequence already has graphics called BLUDA0, BLUDB0 and BLUDC0. We are going to add BLUDD0 and BLUDE0. You can easily make your own graphics using a util like paint shop pro and then include them in a wad file using a tool such as DeePsea. I have included some in the example wad for this tutorial. I will not describe how to do this here. Either use the wad I have made, make your own if you have the know how, or simply use existing doom graphics instead. I will describe how to do use my graphics or existing ones below.
Step 2. We are going to use some of the pain elemental respawn frames, so again set the pain elemental’s respawn frame to 0.
Step 3. In the thing editor, go to the blood splat (thing 39).
Step 4. Reduce its width. This is simply to stop blood splats apparently hanging in mid air when they are actually on the edge of a ledge. With a small value, they will either be on the ledge, or fall off. I set it to 8, it could be smaller.
Step 5. Uncheck bit 4 "can’t be hit". If you leave this checked, the blood pools may stay at the height of the floor they were spawned on. So if it is a rising and falling platform you may end up with a trail of blood hanging in mid air. Unchecking this bit does not cause a problem because the thing is still not set as an obstacle or shootable.
Step 6. Go to the initial frame in the frames box and hit j to jump to it in the frame editor (frame 90). Move down to frame 92, the last normal frame in the blood sequence and change its next frame to 720. I also changed the duration to be slightly shorter as I felt it looked better. If you do not wish to add extra graphics, just set the next frame to be that of a suitable pre existing blood pool (eg frame 957). If you are doing this, save your file, you are finished.
Step 7. Go to frame 720 and change the sprite number to 16 (the BLUD series) and the sub number to 3 (our new BLUDD0 graphic). If you hit the space bar here, dehacked will tell you the graphic doesn’t exist as it only looks in the main doom(2) wad file. That’s ok, we will include the graphic in our own wad.
Step 8. Go to frame 721 and change the sprite number to 16 and the sub number to 4.
Step 9. Change the duration of frame 721 to –1 and the next frame to 0 so that the game never moves from that frame.
Important Footnote: Thanks to Andreas Back (bitstate) for pointing out that you may wish to make the duration of the last frame (721 in this case) very long rather than -1. This would mean the blood splats would eventually disappear rather than staying around forever. Permanent blood splats can make a level fill up with blood. Just load the patch and warp to map20 of doom2 and get the cyberdemon and mastermind fighting and see how much blood a cybie produces before he dies. Lots of blood spots can slow the game down dramatically. A deathmatch game with this patch loaded started to slow down very noticeably after about 30 mins playing on a 1GHz machine using Zdoom when the above patch was loaded. Mind you, the main arena was coated with red :-)
