From 7f6002caba3f0a6749820c2772161caf55b8d267 Mon Sep 17 00:00:00 2001
From: neonloop
Date: Fri, 7 May 2021 20:00:12 +0000
Subject: Initial commit (uqm-0.8.0)

---
 src/uqm/velocity.c | 153 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 src/uqm/velocity.c

(limited to 'src/uqm/velocity.c')

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);
+}
+
-- 
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