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/*
* $Id: renderedge.h,v 1.4 2005/08/24 11:18:33 daniels Exp $
*
* Copyright © 2004 Keith Packard
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of Keith Packard not be used in
* advertising or publicity pertaining to distribution of the software without
* specific, written prior permission. Keith Packard makes no
* representations about the suitability of this software for any purpose. It
* is provided "as is" without express or implied warranty.
*
* KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef _RENDEREDGE_H_
#define _RENDEREDGE_H_
#include "picturestr.h"
#define MAX_ALPHA(n) ((1 << (n)) - 1)
#define N_Y_FRAC(n) ((n) == 1 ? 1 : (1 << ((n)/2)) - 1)
#define N_X_FRAC(n) ((1 << ((n)/2)) + 1)
#define STEP_Y_SMALL(n) (xFixed1 / N_Y_FRAC(n))
#define STEP_Y_BIG(n) (xFixed1 - (N_Y_FRAC(n) - 1) * STEP_Y_SMALL(n))
#define Y_FRAC_FIRST(n) (STEP_Y_SMALL(n) / 2)
#define Y_FRAC_LAST(n) (Y_FRAC_FIRST(n) + (N_Y_FRAC(n) - 1) * STEP_Y_SMALL(n))
#define STEP_X_SMALL(n) (xFixed1 / N_X_FRAC(n))
#define STEP_X_BIG(n) (xFixed1 - (N_X_FRAC(n) - 1) * STEP_X_SMALL(n))
#define X_FRAC_FIRST(n) (STEP_X_SMALL(n) / 2)
#define X_FRAC_LAST(n) (X_FRAC_FIRST(n) + (N_X_FRAC(n) - 1) * STEP_X_SMALL(n))
#define RenderSamplesX(x,n) ((n) == 1 ? 0 : (xFixedFrac (x) + X_FRAC_FIRST(n)) / STEP_X_SMALL(n))
/*
* An edge structure. This represents a single polygon edge
* and can be quickly stepped across small or large gaps in the
* sample grid
*/
typedef struct {
xFixed x;
xFixed e;
xFixed stepx;
xFixed signdx;
xFixed dy;
xFixed dx;
xFixed stepx_small;
xFixed stepx_big;
xFixed dx_small;
xFixed dx_big;
} RenderEdge;
/*
* Step across a small sample grid gap
*/
#define RenderEdgeStepSmall(edge) { \
edge->x += edge->stepx_small; \
edge->e += edge->dx_small; \
if (edge->e > 0) \
{ \
edge->e -= edge->dy; \
edge->x += edge->signdx; \
} \
}
/*
* Step across a large sample grid gap
*/
#define RenderEdgeStepBig(edge) { \
edge->x += edge->stepx_big; \
edge->e += edge->dx_big; \
if (edge->e > 0) \
{ \
edge->e -= edge->dy; \
edge->x += edge->signdx; \
} \
}
xFixed
RenderSampleCeilY (xFixed y, int bpp);
xFixed
RenderSampleFloorY (xFixed y, int bpp);
void
RenderEdgeStep (RenderEdge *e, int n);
void
RenderEdgeInit (RenderEdge *e,
int bpp,
xFixed y_start,
xFixed x_top,
xFixed y_top,
xFixed x_bot,
xFixed y_bot);
void
RenderLineFixedEdgeInit (RenderEdge *e,
int bpp,
xFixed y,
xLineFixed *line,
int x_off,
int y_off);
#endif /* _RENDEREDGE_H_ */
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