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2d parallax scrolling a la diablo II

Started by ari556655 Apr 20, 2009 at 3:37 AM 7 replies 7.1k views

Original Post

Apr 20, 2009 at 3:37 AM

I'm working on a 2d isometric engine and am currently attempting to implement the type of parallax scrolling found in diablo II. I began experimenting with scaling just the bottom layer of ground tiles and quickly realized that it seems almost impossible to scale them individually without messing up all of their offsets. This leads me to believed that the bottom layer is rendered normally and then the image of the finished tile layer is manipulated(stretching the bottom and condensing the top) and so on and so fourth for every proceeding layer. I'm hoping someone on here as had experience with such and old and obscure technique and could provide me with some info on how this is to be achieved.

GerardL

Apr 20, 2009 at 3:50 AM

I'm not entirely certain what you are trying to achieve.

However, a suggestion, perhaps usefull, perhaps not:
Render tiles to a texture.
Have a screen sized layer and map texture on this.

You can stretch the texture any way you want to archive different techniques.

ari556655

Apr 20, 2009 at 3:55 AM

How though would one render to an opengl texture?

GerardL

Apr 20, 2009 at 4:30 AM

Don't use opengl myself, but a quick search found:
http://ogltotd.blogspot.com/2006/12/render-to-texture.html

ari556655

Apr 20, 2009 at 7:00 PM

Thanks for the tip about rendering to a texture, I'm still trying to work that out. Meantime, I'm still wondering if anyone has any experience or knowledge with regards to the specific type of parallax scrolling used in Diablo II.

Drilian

Apr 21, 2009 at 1:36 PM

Diablo 2's parallax mode was actually done with 3D hardware- they added a bit of actual 3D perspective to the renderer to get it to do what you see.

Essentially, the tiles were rendered in the ground plane, while the sprites and columns and walls were rendered upright (in full 3D space). When rendered orthographically (i.e. in non-perspective mode), it all looks like a standard, 2D isometric view.

When they'd apply a bit of perspective to it (and it was a subtle bit of perspective - too much and it would look TOO 3D), the foreground would pan a bit more than the background.

ari556655

Apr 27, 2009 at 12:39 PM

Drilian, could I trouble you to be a but more specific with regards to this? I have very very limited experience with 3d stuff in opengl. Do you mean to say that the ground plane is rendered in 2d ortho and that the upright tiles, such as walls, are rendered in 3d as textured quads or as actual 3d geometry?

GerardL

Apr 28, 2009 at 6:42 AM

(I assume Y-axis is up)

If I understand this correctly then you set up a projection matrix with a fov close to 0. (the higher the fov, the more perspective you gain)

Then you render the tiles on the ground plane, the ground plane and therefore all tiles have a normal point up [0,1,0].

The scenery is rendered over this, either as billboards(sprites) or full 3D.

ari556655

Apr 30, 2009 at 5:37 PM

But how is this possible if everyone of my ground tiles, wall tiles, and characters are all 2d textured quads(just sprites)?

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