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