Platforming and slopes

[DustyPorViva]

Anyone have any suggestions on how to accomplish this? I've tried checking for slope tiles ahead of movement, and incrementing the player.y accordingly(if a 45 degree angle, increment player.y the same as speed, if a 22.5 degree angle, half the speed)... but that's proved unreliable, especially at speeds not divisible by .25. Not only that, but it's not a solid detection(for instance, if the player falls on a slope, nothing would happen).

Right now I'm using NPC's and simply using testnpc(since an NPC inherits the shape of the image) to 'stick' the player onto the slope of the NPC in pixel precision, but this is also proving unreliable at higher speeds.

[12171217]

I had something where the world was represented as lines stored in arrays instead of tiles, it handeled slopes easily and perfectly (Just draw a collision mask over the level).

There's tons of examples of line intersection algorithms online, then just find the line you hit's normal and you can work off that.

Alternatively you could just as easily automatically convert the tiles into lines for collision.

[coreys]

Originally Posted by 12171217

I had something where the world was represented as lines stored in arrays instead of tiles, it handeled slopes easily and perfectly (Just draw a collision mask over the level).

There's tons of examples of line intersection algorithms online, then just find the line you hit's normal and you can work off that.

Alternatively you could just as easily automatically convert the tiles into lines for collision.

Well, could come up with an algorithm to create the lines on slopes, just make lines from corner to corner of blocking tiles. The rest could be handled normally.

[12171217]

Originally Posted by coreys

Well, could come up with an algorithm to create the lines on slopes, just make lines from corner to corner of blocking tiles. The rest could be handled normally.

Yeah I said that in the last sentence =P

Only reason I did it manually was because I liked the control.. It added a bit more depth to have the player moving like, a tad up and down on a surface that's actually a flat tile. If you show a tile layer above the player's feet it would look really nice like that, once V6 comes out.

[coreys]

Originally Posted by 12171217

Yeah I said that in the last sentence =P

Only reason I did it manually was because I liked the control.. It added a bit more depth to have the player moving like, a tad up and down on a surface that's actually a flat tile. If you show a tile layer above the player's feet it would look really nice like that, once V6 comes out.

Hm, that's true. It's always nice to allow for flexibility, though I'm thinking the line collision detection would be slower than normal tile collision detection (some more math involved there), which is why I suggested using normal tile collision for everything else. But if the performance difference isn't particularly noticeable would be best to just do it all as you suggested.

[12171217]

Originally Posted by coreys

Hm, that's true. It's always nice to allow for flexibility, though I'm thinking the line collision detection would be slower than normal tile collision detection (some more math involved there), which is why I suggested using normal tile collision for everything else. But if the performance difference isn't particularly noticeable would be best to just do it all as you suggested.

If you segment the level into "zones" of lines, you're only tracing against like 10-15 lines max, really. It's not too intense. I've had a test NPC on N-Pulse where you draw lines around players and they have to slash them (And they use the same line intersection algorithm to detect the point where hit, and they dynamically segement at that point, it's cool =3), and it traces up to around 50 lines at once, as there's no optimization on it whatsoever. Myself, nor other players, have complained with it or visibly slowed down when I used it either.

[coreys]

Well I'm talking about using lines as a base for collision detection

[12171217]

So am I. It's only around 10-15 lines maximum that are being tested against each frame. It's not a lot.

[coreys]

Well then

[DustyPorViva]

Hmm... well I was hoping for something a little less complicated. I really wish there was a nice open-source platformer with good code and physics, since just about every free platformer out there sucks ass.

If I can manage the line intersection that'd be cool, but it'd be automatic(every time you enter the level). Kai did once post a script that translated all walls into an array of lines, along with the ability to detect collisions. What does worry me is that I'd want this to be able to work flawlessly on a gmap, and processing that when player enters a new level would possibly cause a slight hang-up. I should also mention this would be in GS1.

[DustyPorViva]

Hmm, this is what I currently came up with:

PHP Code:

function CheckForSlopes() {
  if (this.vely != 0) return;
  for (i=0;i<4;i+=1/16) {
    if (tiles[playerx+1.5,playery+1.5+i] in this.left45) {
      this.onslope = 1;
      playery = int(playery+i)-((playerx+1.5)%1);
      break;
    }
  }
  if (i == 4) {
    if (this.onslope == 1) playery = int(playery+(this.velx < 0 ? .5 : 0));
    this.onslope = 0;
  }
}