| 1 | /*
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| 2 | * $Id$
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| 3 | *
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| 4 | * Copyright © 2004 Keith Packard
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| 5 | *
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| 6 | * Permission to use, copy, modify, distribute, and sell this software and its
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| 7 | * documentation for any purpose is hereby granted without fee, provided that
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| 8 | * the above copyright notice appear in all copies and that both that
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| 9 | * copyright notice and this permission notice appear in supporting
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| 10 | * documentation, and that the name of Keith Packard not be used in
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| 11 | * advertising or publicity pertaining to distribution of the software without
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| 12 | * specific, written prior permission. Keith Packard makes no
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| 13 | * representations about the suitability of this software for any purpose. It
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| 14 | * is provided "as is" without express or implied warranty.
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| 15 | *
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| 16 | * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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| 17 | * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
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| 18 | * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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| 19 | * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
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| 20 | * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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| 21 | * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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| 22 | * PERFORMANCE OF THIS SOFTWARE.
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| 23 | */
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| 24 |
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| 25 | #ifndef _RENDEREDGE_H_
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| 26 | #define _RENDEREDGE_H_
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| 27 |
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| 28 | #include "picturestr.h"
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| 29 |
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| 30 | #define MAX_ALPHA(n) ((1 << (n)) - 1)
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| 31 | #define N_Y_FRAC(n) ((n) == 1 ? 1 : (1 << ((n)/2)) - 1)
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| 32 | #define N_X_FRAC(n) ((1 << ((n)/2)) + 1)
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| 33 |
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| 34 | #define STEP_Y_SMALL(n) (xFixed1 / N_Y_FRAC(n))
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| 35 | #define STEP_Y_BIG(n) (xFixed1 - (N_Y_FRAC(n) - 1) * STEP_Y_SMALL(n))
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| 36 |
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| 37 | #define Y_FRAC_FIRST(n) (STEP_Y_SMALL(n) / 2)
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| 38 | #define Y_FRAC_LAST(n) (Y_FRAC_FIRST(n) + (N_Y_FRAC(n) - 1) * STEP_Y_SMALL(n))
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| 39 |
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| 40 | #define STEP_X_SMALL(n) (xFixed1 / N_X_FRAC(n))
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| 41 | #define STEP_X_BIG(n) (xFixed1 - (N_X_FRAC(n) - 1) * STEP_X_SMALL(n))
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| 42 |
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| 43 | #define X_FRAC_FIRST(n) (STEP_X_SMALL(n) / 2)
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| 44 | #define X_FRAC_LAST(n) (X_FRAC_FIRST(n) + (N_X_FRAC(n) - 1) * STEP_X_SMALL(n))
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| 45 |
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| 46 | #define RenderSamplesX(x,n) ((n) == 1 ? 0 : (xFixedFrac (x) + X_FRAC_FIRST(n)) / STEP_X_SMALL(n))
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| 47 |
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| 48 | /*
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| 49 | * An edge structure. This represents a single polygon edge
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| 50 | * and can be quickly stepped across small or large gaps in the
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| 51 | * sample grid
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| 52 | */
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| 53 |
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| 54 | typedef struct {
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| 55 | xFixed x;
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| 56 | xFixed e;
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| 57 | xFixed stepx;
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| 58 | xFixed signdx;
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| 59 | xFixed dy;
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| 60 | xFixed dx;
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| 61 |
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| 62 | xFixed stepx_small;
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| 63 | xFixed stepx_big;
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| 64 | xFixed dx_small;
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| 65 | xFixed dx_big;
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| 66 | } RenderEdge;
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| 67 |
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| 68 | /*
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| 69 | * Step across a small sample grid gap
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| 70 | */
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| 71 | #define RenderEdgeStepSmall(edge) { \
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| 72 | edge->x += edge->stepx_small; \
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| 73 | edge->e += edge->dx_small; \
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| 74 | if (edge->e > 0) \
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| 75 | { \
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| 76 | edge->e -= edge->dy; \
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| 77 | edge->x += edge->signdx; \
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| 78 | } \
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| 79 | }
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| 80 |
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| 81 | /*
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| 82 | * Step across a large sample grid gap
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| 83 | */
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| 84 | #define RenderEdgeStepBig(edge) { \
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| 85 | edge->x += edge->stepx_big; \
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| 86 | edge->e += edge->dx_big; \
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| 87 | if (edge->e > 0) \
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| 88 | { \
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| 89 | edge->e -= edge->dy; \
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| 90 | edge->x += edge->signdx; \
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| 91 | } \
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| 92 | }
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| 93 |
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| 94 | xFixed
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| 95 | RenderSampleCeilY (xFixed y, int bpp);
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| 96 |
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| 97 | xFixed
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| 98 | RenderSampleFloorY (xFixed y, int bpp);
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| 99 |
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| 100 | void
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| 101 | RenderEdgeStep (RenderEdge *e, int n);
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| 102 |
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| 103 | void
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| 104 | RenderEdgeInit (RenderEdge *e,
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| 105 | int bpp,
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| 106 | xFixed y_start,
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| 107 | xFixed x_top,
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| 108 | xFixed y_top,
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| 109 | xFixed x_bot,
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| 110 | xFixed y_bot);
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| 111 |
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| 112 | void
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| 113 | RenderLineFixedEdgeInit (RenderEdge *e,
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| 114 | int bpp,
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| 115 | xFixed y,
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| 116 | xLineFixed *line,
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| 117 | int x_off,
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| 118 | int y_off);
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| 119 |
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| 120 | #endif /* _RENDEREDGE_H_ */
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