Comanche

This website is outdated. The new site with a detailed description can be found here

HTML 5 version

Use the cursor keys or the keys w a s d to move, the keys r and f to change the height and the keys e and q to look down or up.

It was in the year 1992 when I saw pictures of the upcoming game Comanche from Novalogic. The graphics were awesome and in my opinion 5 years ahead of its time. During that time 3D Graphic accelerators were unknown or unaffordable. Comanche uses a technique called voxel space similar to raycasting. To display the landscape a 1024*1024 one byte height map and a 1024*1024 color map is used which you can download on this site. The algorithm draws vertical lines by shooting a ray from the camera into the map. The following figure demonstrate this technique.

The algorithm is briefly described as follows.

Clear Screen.
For every column of the screen define a light ray which starts at the camera and ends at the horizon somewhere far away. The figure shows the direction of the rays.
Divide the ray into very small segments so that every pixel of map under the line is considered.
Load the height and color from the 2D maps corresponding to the position of the ray.
Do some perspective corrections for the height coordinate.
Draw a vertical line with the corresponding color with the height retrieved from the perspective correction.

There are of course a lot of tricks to get higher performance not mentioned here.