warzone2100/lib/ivis_common/pieclip.c

/*
	This file is part of Warzone 2100.
	Copyright (C) 1999-2004  Eidos Interactive
	Copyright (C) 2005-2007  Warzone Resurrection Project

	Warzone 2100 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.

	Warzone 2100 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 Warzone 2100; if not, write to the Free Software
	Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "pieclip.h"
#include "ivi.h"

static UDWORD videoBufferDepth = 32, videoBufferWidth = 640, videoBufferHeight = 480;
extern iSurface	*psRendSurface;

BOOL pie_SetVideoBufferDepth(UDWORD depth)
{
	videoBufferDepth = depth;
	return(TRUE);
}

BOOL pie_SetVideoBufferWidth(UDWORD width)
{
	videoBufferWidth = width;
	return(TRUE);
}

BOOL pie_SetVideoBufferHeight(UDWORD height)
{
	videoBufferHeight = height;
	return(TRUE);
}

UDWORD pie_GetVideoBufferDepth(void)
{
	return(videoBufferDepth);
}

UDWORD pie_GetVideoBufferWidth(void)
{
	return(videoBufferWidth);
}

UDWORD pie_GetVideoBufferHeight(void)
{
	return(videoBufferHeight);
}

void pie_Set2DClip(int x0, int y0, int x1, int y1)
{
	psRendSurface->clip.left = x0;
	psRendSurface->clip.top = y0;
	psRendSurface->clip.right = x1;
	psRendSurface->clip.bottom = y1;
}

static void pie_ClipUV(PIEVERTEX *s1, PIEVERTEX *s2, PIEVERTEX *clip, Sint32 t)
{
	clip->u = s1->u + ((t * (s2->u - s1->u)) >> iV_DIVSHIFT);
	clip->v = s1->v + ((t * (s2->v - s1->v)) >> iV_DIVSHIFT);
	clip->z = s1->z + ((t * (s2->z - s1->z)) >> iV_DIVSHIFT);

	clip->light.byte.r = s1->light.byte.r + ((t * (s2->light.byte.r - s1->light.byte.r)) >> iV_DIVSHIFT);
	clip->light.byte.g = s1->light.byte.g + ((t * (s2->light.byte.g - s1->light.byte.g)) >> iV_DIVSHIFT);
	clip->light.byte.b = s1->light.byte.b + ((t * (s2->light.byte.b - s1->light.byte.b)) >> iV_DIVSHIFT);
	clip->light.byte.a = s1->light.byte.a + ((t * (s2->light.byte.a - s1->light.byte.a)) >> iV_DIVSHIFT);
}

static int pie_ClipXT(PIEVERTEX *s1, PIEVERTEX *s2, PIEVERTEX *clip)
{
	int n = 1, dx;
	Sint32 t;

	if (s2->x >= s1->x)
	{
		if (s1->x < psRendSurface->clip.left)
		{
			if (s2->x <= psRendSurface->clip.left)
				return 0;

			dx = s2->x - s1->x;

			if (dx != 0)
			{
				clip->y = s1->y + (s2->y - s1->y) * (psRendSurface->clip.left - s1->x) / dx;
			}
			else
			{
				clip->y = s1->y;
			}

			clip->x = psRendSurface->clip.left;

			// clip uv
			t = ((clip->x - s1->x) << iV_DIVSHIFT) / dx;
			pie_ClipUV(s1, s2, clip, t);
		}
		else
		{
			*clip = *s1;
		}

		if (s2->x > psRendSurface->clip.right)
		{
			if (s1->x > psRendSurface->clip.right)
				return 0;

			clip++;
			dx = s2->x - s1->x;

			if (dx != 0)
			{
				clip->y = s2->y - (s2->y - s1->y) * (s2->x - psRendSurface->clip.right) / dx;
			}
			else
			{
				clip->y = s2->y;
			}

			clip->x = psRendSurface->clip.right;

			// clip uv
			t = ((clip->x - s1->x) << iV_DIVSHIFT) / dx;
			pie_ClipUV(s1, s2, clip, t);

			n = 2;
		}

		return n;
	}
	else
	{
		if (s1->x > psRendSurface->clip.right)
		{
			if (s2->x >= psRendSurface->clip.right)
				return 0;

			dx = s1->x - s2->x;

			if (dx != 0)
			{
				clip->y = s1->y - (s1->y - s2->y) * (s1->x - psRendSurface->clip.right) / dx;
			}
			else
			{
				clip->y = s1->y;
			}

			clip->x = psRendSurface->clip.right;

			// clip uv
			t = ((clip->x - s1->x) << iV_DIVSHIFT) / dx;
			pie_ClipUV(s1, s2, clip, t);
		}
		else
		{
			*clip = *s1;
		}

		if (s2->x < psRendSurface->clip.left)
		{
			if (s1->x < psRendSurface->clip.left)
				return 0;

			clip++;
			dx = s1->x - s2->x;

			if (dx != 0)
			{
				clip->y = s2->y + (s1->y - s2->y) * (psRendSurface->clip.left - s2->x) / dx;
			}
			else
			{
				clip->y = s2->y;
			}

			clip->x = psRendSurface->clip.left;

			// clip uv
			t = ((clip->x - s1->x)<<iV_DIVSHIFT) / dx;
			pie_ClipUV(s1, s2, clip, t);

			n = 2;
		}

		return n;
	}
}

static int pie_ClipYT(PIEVERTEX *s1, PIEVERTEX *s2, PIEVERTEX *clip)
{
	int n = 1, dy;
	Sint32 t;

	if (s2->y >= s1->y)
	{
		if (s1->y < psRendSurface->clip.top)
		{
			if (s2->y <= psRendSurface->clip.top)
				return 0;

			dy = s2->y - s1->y;

			if (dy != 0)
			{
				clip->x = s1->x + (s2->x - s1->x) * (psRendSurface->clip.top - s1->y) / dy;
			}
			else
			{
				clip->x = s1->x;
			}

			clip->y = psRendSurface->clip.top;

			// clip uv
			t = ((clip->y - s1->y) << iV_DIVSHIFT) / dy;
			pie_ClipUV(s1, s2, clip, t);
		}
		else
		{
			*clip = *s1;
		}

		if (s2->y > psRendSurface->clip.bottom)
		{
			if (s1->y > psRendSurface->clip.bottom)
			{
				return 0;
			}

			clip++;

			dy = s2->y - s1->y;

			if (dy != 0)
			{
				clip->x = s2->x - (s2->x - s1->x) * (s2->y - psRendSurface->clip.bottom) / dy;
			}
			else
			{
				clip->x = s2->x;
			}

			clip->y = psRendSurface->clip.bottom;

			t = ((clip->y - s1->y) << iV_DIVSHIFT) / dy;
			pie_ClipUV(s1, s2, clip, t);

			n = 2;
		}

		return n;

	}
	else
	{
		if (s1->y > psRendSurface->clip.bottom)
		{
			if (s2->y >= psRendSurface->clip.bottom)
				return 0;

			dy = s1->y - s2->y;

			if (dy != 0)
			{
				clip->x = s1->x - (s1->x - s2->x) * (s1->y - psRendSurface->clip.bottom) / dy;
			}
			else
			{
				clip->x = s1->x;
			}

			clip->y = psRendSurface->clip.bottom;

			// clip uv
			t = ((clip->y - s1->y) << iV_DIVSHIFT) / dy;
			pie_ClipUV(s1, s2, clip, t);

		}
		else
		{
			*clip = *s1;
		}

		if (s2->y < psRendSurface->clip.top)
		{
			if (s1->y < psRendSurface->clip.top)
			{
				return 0;
			}

			clip++;

			dy = s1->y - s2->y;

			if (dy != 0)
			{
				clip->x = s2->x + (s1->x - s2->x) * (psRendSurface->clip.top - s2->y) / dy;
			}
			else
			{
				clip->x = s2->x;
			}

			clip->y = psRendSurface->clip.top;

			t = ((clip->y - s1->y) << iV_DIVSHIFT) / dy;
			pie_ClipUV(s1, s2, clip, t);

			n = 2;
		}

		return n;
	}
}

int pie_ClipTextured(int npoints, PIEVERTEX *points, PIEVERTEX *clip)
{
	static PIEVERTEX xclip[iV_POLY_MAX_POINTS+4];
	PIEVERTEX *p0, *p1;
	int n1, n, i;

	p0 = &points[0];
	p1 = &points[1];

	for (i = 0, n1 = 0; i < npoints; i++, p0++, p1++)
	{
		if (i == (npoints-1))
			p1 = &points[0];

		// FIXME MAGIC
		if ((p0->x == 1<<15) || (p0->y == -1<<15))//check for invalid points jps19aug97
			return 0;

		n1 += pie_ClipXT(p0, p1, &xclip[n1]);
	}

	p0 = &xclip[0];
	p1 = &xclip[1];

	for (i = 0, n = 0; i < n1; p0++, p1++, i++)
	{
		if (i == (n1-1))
			p1 = &xclip[0];
		n += pie_ClipYT(p0, p1, &clip[n]);
	}

	return n;
}

#ifdef NEVER_USED_ANYWHERE
// I leave this around just for potential inspirational purposes. - Per

//*************************************************************************
/* Alex - much faster tri clipper - won't clip owt else tho' */
int	pie_ClipTexturedTriangleFast(PIEVERTEX *v1, PIEVERTEX *v2, PIEVERTEX *v3, PIEVERTEX *clipped)
{
	static	PIEVERTEX	xClip[iV_POLY_MAX_POINTS+4];	// plus 4 hopefully is limit?
	static	PIEVERTEX	*p0,*p1;
	UDWORD	numPreY,numAll;
	UDWORD	i;

	numPreY = 0;
	if( (v1->x > LONG_TEST) || (v1->y > LONG_TEST) )
	{
		/* bomb out for out of range points */
		return(0);
	}
	numPreY += pie_ClipXT(v1, v2, &xClip[numPreY]);

	if( (v2->x > LONG_TEST) || (v2->y > LONG_TEST) )
	{
		/* bomb out for out of range points */
		return(0);
	}
	numPreY += pie_ClipXT(v2, v3, &xClip[numPreY]);

	if( (v3->x > LONG_TEST) || (v3->y > LONG_TEST) )
	{
		/* bomb out for out of range points */
		return(0);
	}
	numPreY += pie_ClipXT(v3, v1, &xClip[numPreY]);

	/* We've now clipped against x axis - now for Y */

	p0 = &xClip[0];
	p1 = &xClip[1];

	for (i = 0, numAll = 0; i <n umPreY; p0++, p1++, i++) {
		if (i == (numPreY-1))
			p1 = &xClip[0];
		numAll += pie_ClipYT(p0, p1, &clipped[numAll]);
	}

	return numAll;
}
#endif