Tiberian Dawn Creating a mission height map for C&C64

[Nyerguds]

With Kamuix writing a guide on inserting maps into the N64 version, I got busy looking into how it would be possible to more-or-less automatically generate height maps of C&C maps, so inserted maps actually look good in N64.

It took me a couple of tries, but finally I managed to create a set of tools to convert maps to height maps. All of these are contained inside the CnC64 File Converter. (v1.0.3 or higher)

 

The basics:

C&C terrain is not three-dimensional, but gives an illusion of 3D with the images on the cliffs. However, this illusion falls flat (literally) in a real 3D environment. To remedy this problem, they added greyscale images to the missions in N64 that indicate the elevation of the terrain (brighter = higher). So if you want to import maps into an N64 ROM and have them actually look good, they are going to need a height map too.

Elevation is not done per cell, but on the four corners of each cell. Because of this, the height map images have a size of 65x65, whereas C&C maps are only 64x64 cells. However, the converter takes care of that automatically, so we'll just focus on making a 64x64 height map.

The basic steps to make an image using the CnC64 File Converter:

• Open a map file, and convert it to a basic terrain levels image. This image will contain only the cliffs of the map.
• Save the terrain levels image and edit it in an image editor, and fill areas surrounded by cliffs with the colour for that level. If multiple levels are needed, use the brighter colors in the image's palette. There are 4 elevation levels that can be used.
• Open the map in the File Converter again, and generate the height map, using the terrain levels image you created.
• Convert the final image to 65x65 height map, and save it as paletteless N64 IMG format.

The detailed steps:

 

1. Convert a map to a basic levels image:

Open the map you want to make a height map for. The process works best if there's a .ini file with it that tells the program which theater the map is, and how big the actual used area on the map is. The ini file itself will not be accepted by the program, so open either the .bin file, or the already-converted .map for the N64.

Open the "Convert" menu, go to "Height map generation", and select "To basic levels image (from map)". This option will only work if you have a map loaded.

You will end up with an image which has a dark gray background, and only the cliffs on it, in a slightly brighter gray. Note that this is a paletted image with five colours; even if the image is later saved as high-colour, it will be matched back to these five colours to be interpreted as height levels.

As you see, the image has some modifications compared to the original; the conversion takes the last terrain types encountered at the edges of the actually used portion of the map, and stretches them to the full frame. This is done so cliffs placed outside a map's border to control reinforcements would not influence the height map.

Note that the image is not saved yet at this point, so press Ctrl+S and save it to disk.

 

2. Create the height levels image:

Now the real work. Open the saved image file in your favourite image editor, and connect the cliffs to form closed areas. To do this correctly, open the map itself in a map editor so you can see the directions of the cliffs, and see what kind of elevation each area should have. Here's my process in a few steps:

It doesn't matter if the image is saved in high colours, but as noted before, the converter will match it back to the five colours in the original image's palette, so there's no use in making detailed slopes in this. Its only function is to separate the terrain into levels.

For the record, the grey tints used for the five levels are:

• #000000 (R=0, G=0, B=0) : Pure black. Shouldn't be used, since water creates a slight depression into terrain, and you can't do that on the lowest level.
• #404040 (R=64, G=64, B=64) : Basic terrain. This will be the starting level on the image, and should be seen as lowest level you can use.
• #808080 (R=128, G=128, B=128) : Cliffs elevation #1
• #C0C0C0 (R=192, G=192, B=192) : Cliffs elevation #2
• #FFFFFF (R=255, G=255, B=255) : Cliffs elevation #3. Note that this is the highest possible level, and no more terrain details can be put on top of this. Rivers should work, though, since they decrease the terrain.

Anyway, with that done, we end up with our terrain levels image:

 

3. Creating the actual (64x64) height map

Now we got our levels image this is fairly simple. Once again, load the map into the converter program. Open the "Convert" menu, go to "Height map generation", and now select "To height map using levels (from map)".

It will ask you to select the height levels image. Select the final product of our work from the previous step.

Now the real magic happens. It will generate an image that adapts the terrain to the new heights, and if your cliffs match your levels image correctly, it will make sharp elevations for the cliffs and smooth slopes for the openings where the level decreases on non-cliff terrain. Furthermore, the height of rivers and other water will be applied on each specific level.

Once this step is done, feel free to save the image if you want to add some more specific tweaks to it, or fix any errors the generator might have made. If you think the map is good enough, though, you can continue straight to the next step.

 

4. Converting the height map to the final format

So we got a 64x64 height map image now, loaded into the converter. The N64 game not only needs the image to be 65x65, but also needs it saved in the specific paletteless IMG format.

First things first: go to "Convert", "Height map generation", and select the final option: "To 65x65 height map image (from image)". As you see, this is the only option in there that doesn't use a C&C map as input but an image.

Select it, and the 64x64 data will be centered in a 65x65 frame, creating smoother edges everywhere.

Starting from v1.04, the image in the editor will automatically identify itself as paletteless N64 image, so all you need to do is press Ctrl+S to save it in the correct format.

...and that's it! You have your height map, ready to insert into the ROM. The name format the game looks for is exactly the same as for the .ini and the .bin, just with .img as file extension.

Edited October 28, 2021 by Nyerguds
fixed images

[Chad1233]

Good work Nyerguds! Now we need a full blown unit editor for the game.