diff options
Diffstat (limited to 'src/uqm/velocity.c')
| -rw-r--r-- | src/uqm/velocity.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/src/uqm/velocity.c b/src/uqm/velocity.c new file mode 100644 index 0000000..5e39f02 --- /dev/null +++ b/src/uqm/velocity.c @@ -0,0 +1,153 @@ +//Copyright Paul Reiche, Fred Ford. 1992-2002 + +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ + +#include "velocity.h" + +#include "units.h" +#include "libs/compiler.h" + + +#define VELOCITY_REMAINDER(v) ((v) & (VELOCITY_SCALE - 1)) + +void +GetCurrentVelocityComponents (VELOCITY_DESC *velocityptr, SIZE *pdx, SIZE *pdy) +{ + *pdx = WORLD_TO_VELOCITY (velocityptr->vector.width) + + (velocityptr->fract.width - (SIZE)HIBYTE (velocityptr->incr.width)); + *pdy = WORLD_TO_VELOCITY (velocityptr->vector.height) + + (velocityptr->fract.height - (SIZE)HIBYTE (velocityptr->incr.height)); +} + +void +GetNextVelocityComponents (VELOCITY_DESC *velocityptr, SIZE *pdx, SIZE *pdy, + COUNT num_frames) +{ + COUNT e; + + e = (COUNT)((COUNT)velocityptr->error.width + + ((COUNT)velocityptr->fract.width * num_frames)); + *pdx = (velocityptr->vector.width * num_frames) + + ((SIZE)((SBYTE)LOBYTE (velocityptr->incr.width)) + * (e >> VELOCITY_SHIFT)); + velocityptr->error.width = VELOCITY_REMAINDER (e); + + e = (COUNT)((COUNT)velocityptr->error.height + + ((COUNT)velocityptr->fract.height * num_frames)); + *pdy = (velocityptr->vector.height * num_frames) + + ((SIZE)((SBYTE)LOBYTE (velocityptr->incr.height)) + * (e >> VELOCITY_SHIFT)); + velocityptr->error.height = VELOCITY_REMAINDER (e); +} + +void +SetVelocityVector (VELOCITY_DESC *velocityptr, SIZE magnitude, COUNT facing) +{ + COUNT angle; + SIZE dx, dy; + + angle = velocityptr->TravelAngle = + FACING_TO_ANGLE (NORMALIZE_FACING (facing)); + magnitude = WORLD_TO_VELOCITY (magnitude); + dx = COSINE (angle, magnitude); + dy = SINE (angle, magnitude); + if (dx >= 0) + { + velocityptr->vector.width = VELOCITY_TO_WORLD (dx); + velocityptr->incr.width = MAKE_WORD ((BYTE)1, (BYTE)0); + } + else + { + dx = -dx; + velocityptr->vector.width = -VELOCITY_TO_WORLD (dx); + velocityptr->incr.width = + MAKE_WORD ((BYTE)0xFF, (BYTE)(VELOCITY_REMAINDER (dx) << 1)); + } + if (dy >= 0) + { + velocityptr->vector.height = VELOCITY_TO_WORLD (dy); + velocityptr->incr.height = MAKE_WORD ((BYTE)1, (BYTE)0); + } + else + { + dy = -dy; + velocityptr->vector.height = -VELOCITY_TO_WORLD (dy); + velocityptr->incr.height = + MAKE_WORD ((BYTE)0xFF, (BYTE)(VELOCITY_REMAINDER (dy) << 1)); + } + + velocityptr->fract.width = VELOCITY_REMAINDER (dx); + velocityptr->fract.height = VELOCITY_REMAINDER (dy); + velocityptr->error.width = velocityptr->error.height = 0; +} + +void +SetVelocityComponents (VELOCITY_DESC *velocityptr, SIZE dx, SIZE dy) +{ + COUNT angle; + + if ((angle = ARCTAN (dx, dy)) == FULL_CIRCLE) + { + ZeroVelocityComponents (velocityptr); + } + else + { + if (dx >= 0) + { + velocityptr->vector.width = VELOCITY_TO_WORLD (dx); + velocityptr->incr.width = MAKE_WORD ((BYTE)1, (BYTE)0); + } + else + { + dx = -dx; + velocityptr->vector.width = -VELOCITY_TO_WORLD (dx); + velocityptr->incr.width = + MAKE_WORD ((BYTE)0xFF, (BYTE)(VELOCITY_REMAINDER (dx) << 1)); + } + if (dy >= 0) + { + velocityptr->vector.height = VELOCITY_TO_WORLD (dy); + velocityptr->incr.height = MAKE_WORD ((BYTE)1, (BYTE)0); + } + else + { + dy = -dy; + velocityptr->vector.height = -VELOCITY_TO_WORLD (dy); + velocityptr->incr.height = + MAKE_WORD ((BYTE)0xFF, (BYTE)(VELOCITY_REMAINDER (dy) << 1)); + } + + velocityptr->fract.width = VELOCITY_REMAINDER (dx); + velocityptr->fract.height = VELOCITY_REMAINDER (dy); + velocityptr->error.width = velocityptr->error.height = 0; + } + + velocityptr->TravelAngle = angle; +} + +void +DeltaVelocityComponents (VELOCITY_DESC *velocityptr, SIZE dx, SIZE dy) +{ + + dx += WORLD_TO_VELOCITY (velocityptr->vector.width) + + (velocityptr->fract.width - (SIZE)HIBYTE (velocityptr->incr.width)); + dy += WORLD_TO_VELOCITY (velocityptr->vector.height) + + (velocityptr->fract.height - (SIZE)HIBYTE (velocityptr->incr.height)); + + SetVelocityComponents (velocityptr, dx, dy); +} + |