The world map in Sacred 2 not just opened up. It burned in and out! How this looks, is proudly presented by this little GIF animation:

Source: Sacred 2

So how is such an effect possible? I can’t tell you the deep technical details, because i didn’t understand them. But let me try to explain it in artist words.
First you paint a height map. There should be one dominant spike in it, depending how you want the map to burn in/out. And now imagine how this map would look like in geometry:
When you think about to press this “mountain” from below through a paper it would look like that:
And this is exactly what happens. Of course not with a 3D model but the shader checks the height map and the current “paper” height, generates a alpha mask from it and this mask is then used for the map animation.

If you now raise your hand and ask “But where comes the burning border from?”, then you’re a A+ pupil. As before i can’t explain how it really works, but there’s just one small gradient texture which is “wrapped” around the borders of the generated alpha mask:

Source: Sacred 2

Update 1
Kyle just posted his breakdown of his burning-paper-effect in the comments!

8 thoughts on “Sacred 2 – Burning Map

  1. Bryan Holmes

    If I had to guess, I’d say that they have a heightmap, and rotate the gradient texture. So lets say your height map goes from 1.0 to 0.0 and you start with a variable X of 0.99

    Anything at X gets painted yellow, and the lower you go towards 0.0, the more you move to the right of yellow on the alpha mask. Anything above X (to a max of 1.0) gets painted to the left (which is clear).

    So you draw the screen from the camera, but you draw the map whenever you have alpha pixels. Move X down gradually, from 0.99 to 0.0 and then everything will be alpha (in otherwords, map). Because you’re scaling down X, everything that WAS X before is now clear, and the new X is yellow.

    Reply
    1. Simon

      Thank for your comment!

      The embarrassing fact is, that i worked on the game and asked the coder who did this effect. But after years some things get forgotten and so he couldn’t say exactly how he did it. :D

      Reply
        1. Simon Post author

          Sure. I was an artist and produced some assets. My portfolio shows some of them. :)

          Reply
  2. Florian Noirbent

    Hi,
    I just found your blog and there is a lot of interesting stuff, keep up the good work.
    I hope it wont be seen as advertising, but I made an Fx like this few weeks ago (but in 3D) with unity’s surface shader. This is not a big deal, but the source is available if you want to check it out: http://florian-noirbent.com/blog/en/disappear-objects-shader/ .
    By the way, the idea of a ramp instead of a plain color for transitions is awesome, maybe I’ll update mine.

    Reply

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