Bug #919: [Doom] Blast damage algorithm - Doomsday Engine - Tracker

Bug #919

[Doom] Blast damage algorithm

Added by gobhuo almost 14 years ago. Updated about 7 years ago.

Status:

New

Priority:

Normal

Assignee:

Category:

Vanilla emulation

Target version:

Vanilla / Gameplay

Start date:

2010-06-10

% Done:

Tags:

Doom, PlaySim, Physics

Description

Responding to your last comment in http://sourceforge.net/tracker/?func=detail&aid=2929822&group_id=74815&atid=542099 ;
I think that the new method is still incorrect, as it treats z-axis differently from x and y. In effect, to calculate damage, you calculate distance from a blast to a "concentric" horisontal square. This violates the rule: if explosion happens on object's bounding box, it deals full damage. I think you should use the distance from bounding box instead.

I just thought that arch-vile's attack damage could be incorrect because of this. And indeed: with "server-game-radiusattack-nomaxz 1" damage is usually 82 (practically correct), with "server-game-radiusattack-nomaxz 0" it's usually 78. In PrBoom+, v1.9 compatibility, it's 84. Tested on MAP11 @ doom2.wad, standing still.

Labels: Gameplay

History

#1 Updated by vermil almost 14 years ago

One should test in the original Doom2.exe and not PrBoom+ or any other source port.

#2 Updated by vermil almost 14 years ago

Indeed, I've just tested in Doom2.exe and Doom95 and got 83 every time.

Hence PrBoom+ 's 84 is wrong as well.

#3 Updated by danij almost 14 years ago

The world up axis is treated the same as the other axes it just depends on the value of server-game-radius-attack-nomaxz as to how many axes are involved in the distance calculation.

Vanilla DOOM does it in 2D (same as server-game-radius-attack-nomaxz=1) whereas we do it in 3D by default.

Here is the actual code in question:

dx = fabs(thing->pos[VX] - bombSpot->pos[VX]);
    dy = fabs(thing->pos[VY] - bombSpot->pos[VY]);
    dz = fabs((thing->pos[VZ] + thing->height / 2) - bombSpot->pos[VZ]);

dist = (dx > dy? dx : dy);

if(!cfg.netNoMaxZRadiusAttack) // "server-game-radiusattack-nomaxz" 
        dist = (dz > dist? dz : dist);

dist = (dist - thing->radius);

The dist value is then fed into the damage equation:

damage = (bombDamage * (bombDistance - dist) / bombDistance) + 1;

#4 Updated by gobhuo over 13 years ago

dx = fabs(thing->pos[VX] - bombSpot->pos[VX]);
dy = fabs(thing->pos[VY] - bombSpot->pos[VY]);

dist = (dx > dy? dx : dy);
dist = (dist - thing->radius);//subtract thing's radius here instead of in dx and dy expressions as an optimisation;
//hence it must precede z-related modification of dist.

dz = fabs((thing->pos[VZ] + thing->height / 2) - bombSpot->pos[VZ]) - thing->height / 2; //it was wrong here and in the location of dist = (dist - thing->radius) expression
if(!cfg.netNoMaxZRadiusAttack) // "server-game-radiusattack-nomaxz"
dist = (dz > dist? dz : dist);

//This should truly treat all axes the same.