[korndog]

I am curious as to how others are drawing their sprites in back-to-front order. Right now my engine is mergesorting a linked-list of NPCs by their y-coordinate each frame. I usually have 20 sprite-based NPCs a map (the rest being tiles) so it works out to six list passes a frame.

I've worked on five rpg engines and this, more or less, is the way I've always done sprite drawing. What do you do?

[Bjorn]

In our engine the use of particle effects or other exessive use of objects such as lamp posts and decoration makes for possibly hundreds of sprites. Each frame, the engine goes through all of them checking their visibity. Usually only 1-20 objects are visible and they are sorted on y+z order using the STL sort implementation.

[Sirocco(lazy)]

I normally sort by Y/Z coords, where Y (depth) has priority and Z (height) is secondary... I know that's backwards from standard mathematical references, but I hardly care ;)

Check for visibility, then pass list to the drawing routine for masking, etc.

Fun.

[Mandrake]

I usually create two arrays, one for sprites, and another for drawing order. This may seem like an overkill, but the second array is really a series of sprite refrences, and can have multiple refrences for the same sprite. This is good for a town, or a platform/shmup style game where you have a lot of repeating sprites. It works sort of like the old infinte bobs demo in the old demo scene. The first array is just basically graphics, with no extra information. The second array contains teh x, y, z values and the sprite's refrenece to the actual graphic.

You would then check for visibility (in the second array), sort them into a ressonable drawing order, then draw them to the screen. The nice thing is, the first array (with the actual graphics) is not touched until the drawing method is invoked. I usually use a quicksort based algoyrhtm I've concocted for sorting the values.
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[korndog]

I hadn't though of checking visibility before sorting... most of my test maps have been tiny abstract worlds, heh. The code I've done doesn't have any particle fx or anything.
Mandrake, I do something like that too. The NPCs in the list point to an animation array, and those point to pictures in a picture array.

Thanks for your replies.

[golrien]

See, I use a bubblesort for y-sorting, because in this case it's mostly just looping around.. because the ssprites don't do an insane amount of moving, it's quite possibly the fastest. Then again, I guess a quicksort would loop through just as fast on already-sorted sprites, I just understand bubble sort better :)

[LeoDraco]