DDrop - 2D Action RPG

randomshade

Level 1

Fastzelda

« Reply #20 on: December 31, 2012, 11:18:22 AM »

For some strange reason (*cough* the wife's wishes) we decided to move over the holidays, which when coupled with the holidays has meant not a whole lot of progress the last couple of weeks. With some luck, we'll get internet at our new place this Thursday and then hopefully sanity ensues...

Last week I did get started on the implementation for traps. A lot of the annoying leg work is done, and now I just need to flesh out the various types and triggers. The simplest to implement was a projectile trap. It is exactly as it sounds: when triggered, it fires off some kind of projectile, be it a fireball, arrow, poison gas cloud, or whatever. In many ways, projectile traps are just a special case of emitter so it was only a couple of hours of work to get something basic up and running.

Of slightly more importance, I *finally* tracked down an awful performance bug that was murdering the CPU. I was convinced that there was something vile going on in the physics system, which turned out to be totally incorrect (although the physics system was a prime manifestation of the issue.) It actually turned out to be some simple evil of leaving in debug code where it shouldn't be and that debug code being horrendously broken anyway. (Performing dynamic string copies on *every* single random element access = very, very bad.) The net result of that fix was instead of blitzing the CPU during physics solving with only 40-50 on screen entities, we can now solve for many hundreds/low thousands of closely situated objects. Since basically everything in the game is physically interactive (character, enemies, projectiles, objects, debris, coins, items) squashing this bug will finally let me sleep better at night.

And in celebration of axing that bug, I present a short video with a lot of fireball spewing altars and a lot of goblins. Just a bit of fun :D

At some point, I want to write about our data system (short story: xml based that have a high level of readability/correspondence to game object hierarchy and support for [nested] templates) but that post will take forever. So in the meantime, here's a look at the data which drives the basic fireball trap shown in the video.

Fireball Trap
This "trap" just shoots out fireballs in any random direction on a timer, versus being triggered by some event.

Code:

<FireBallTrap_A name="fireball_trap_A">
	<Emitter >
		<Nexus type="point" offsetx="0" offsety="0" size="0.0" slope="0.0"/>
		<Pattern type="arc" dir="0" minangle="0.0" maxangle="360.0" minmag="200.0" maxmag="250.0"/>
		<Burst emitonload="1" numbursts="-1" minemittables="1" maxemittables="1" bursttimer="3.00"/>
		<Emissable class="interactive" database="Object" entry="Fireball" quantity="3" />
	</Emitter>
</FireBallTrap_A>

Fireball Object

Code:

<Fireball name="fireball">
	<Template database="Object" entry="HasBlobShadow" />
	<SceneNode posz="32" />
	<Renderable debugdraw="5" />
	<Sprite file="art/effects/particles/fireball.xml" />
	<Dynamic mass="10.0" cod="0.0" cor="1.0" gravity="0" rotatetoheading="1"/>
	<Collidable type="9" height="28" prop="3">
		<Reaction objtype="4" action="10"/>
		<Reaction objtype="5" action="10"/>
		<Reaction objtype="6" action="10"/>
		<Reaction objtype="7" action="10"/>
		<Reaction objtype="10" action="8"/>
	</Collidable>
	<Interactive maxhp="4" passive_dmg="4" />
	<Entity> <Body iscircle="1" radius="15.0"> <Vert x="0" y="0.0" /> </Body> </Entity>
	<Node class="emitter">
		<SceneNode name="em_destruct"/>
		<Template database="Emitter" entry="BloodSpray"/>
	</Node>
</Fireball>


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jctwood

Level 10