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- handle another precision issue in MoveDude.

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That mulscale16r function is broken enough to affect the values in an observable way that cannot be replicated with real floats.
This commit is contained in:
Christoph Oelckers 2022-10-10 19:32:01 +02:00
parent c9bcfff654
commit 84ce8b29f2
3 changed files with 8 additions and 5 deletions
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9
source/games/blood/src/actor.cpp
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@ -5159,10 +5159,13 @@ void MoveDude(DBloodActor* actor)
return;
if (actor->xspr.height >= 0x100)
return;
double nDrag = gDudeDrag;
int nDrag = gDudeDrag;
if (actor->xspr.height > 0)
nDrag -= Scale(gDudeDrag, (double)actor->xspr.height, 256.);
actor->vel.XY() += -actor->vel * nDrag;
nDrag -= Scale(gDudeDrag, actor->xspr.height, 256);
// this cannot be floatified due to the effect of mulscale16r on the value.
actor->vel.X += FixedToFloat(-mulscale16r(FloatToFixed(actor->vel.X), nDrag));
actor->vel.Y += FixedToFloat(-mulscale16r(FloatToFixed(actor->vel.Y), nDrag));
if (actor->vel.XY().Length() < 0.0625)
actor->ZeroVelocityXY();

2
source/games/blood/src/actor.h
View file

@ -169,7 +169,7 @@ extern const EXPLOSION explodeInfo[];
extern const THINGINFO thingInfo[];
extern VECTORDATA gVectorData[];
const double gDudeDrag = FixedToFloat(0x2a00);
const int gDudeDrag = 0x2a00;
template<typename T> bool IsPlayerSprite(T const * const pSprite)
{

2
source/games/blood/src/common_game.h
View file

@ -605,7 +605,7 @@ inline int scale(int a1, int a2, int a3, int a4, int a5)
return a4 + (a5 - a4) * (a1 - a2) / (a3 - a2);
}
inline int mulscale16r(int a, int b)
inline int mulscale16r(int a, int b) // do not delete!
{
int64_t acc = 1 << (16 - 1);
acc += ((int64_t)a) * b;