Mercurial > hg > dmlib
annotate dmdrawline.h @ 133:92cc5e1fa180
Some work on line drawing routines.
| author | Matti Hamalainen <ccr@tnsp.org> |
|---|---|
| date | Fri, 05 Oct 2012 00:36:40 +0300 |
| parents | 997e26f17946 |
| children | 79dac918c81e |
| rev | line source |
|---|---|
| 0 | 1 |
|
22
997e26f17946
Initial fixes for getting the line drawing functions "working".
Matti Hamalainen <ccr@tnsp.org>
parents:
0
diff
changeset
|
2 static int DM_DRAWLINE_NAME (SDL_Surface *screen, int x0, int y0, int x1, int y1, const Uint32 col) |
| 0 | 3 { |
| 4 int dx, dy, xstep, ystep; | |
| 5 const int qpitch = screen->pitch / DM_DRAWLINE_DST_BYTES; | |
| 6 | |
| 7 // Clipping | |
|
133
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
8 if (dmClipLineCoords(&x0, &y0, &x1, &y1, screen) < 0) |
| 0 | 9 return -1; |
| 10 | |
| 11 // Compute initial deltas | |
| 12 dx = (x1 - x0) * 2; | |
| 13 dy = (y1 - y0) * 2; | |
| 14 | |
|
133
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
15 |
| 0 | 16 if (dx < 0) |
| 17 { | |
| 18 dx = -dx; | |
| 19 xstep = -1; | |
| 20 } | |
| 21 else | |
| 22 xstep = 1; | |
| 23 | |
| 24 if (dy < 0) | |
| 25 { | |
| 26 dy = -dy; | |
| 27 ystep = -qpitch; | |
| 28 } | |
| 29 else | |
| 30 ystep = qpitch; | |
| 31 | |
| 32 // Compute offsets | |
| 33 y0 *= qpitch; | |
| 34 y1 *= qpitch; | |
| 35 | |
|
133
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
36 #ifdef DM_DRAWLINE_INIT |
|
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
37 DM_DRAWLINE_INIT |
|
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
38 #endif |
|
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
39 |
|
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
40 DM_DRAWLINE_DST_TYPE *pix = (DM_DRAWLINE_DST_TYPE *) screen->pixels; |
| 0 | 41 |
| 42 // Continue based on which delta is larger | |
| 43 if (dx > dy) | |
| 44 { | |
| 45 int afrac = dy - (dx / 2); | |
| 46 while (x0 != x1) | |
| 47 { | |
| 48 if (afrac >= 0) | |
| 49 { | |
| 50 y0 += ystep; | |
| 51 afrac -= dx; | |
| 52 } | |
| 53 | |
| 54 x0 += xstep; | |
| 55 afrac += dy; | |
| 56 | |
| 57 DM_DRAWLINE_INNER | |
| 58 } | |
| 59 } | |
| 60 else | |
| 61 { | |
| 62 int afrac = dx - (dy / 2); | |
| 63 while (y0 != y1) | |
| 64 { | |
| 65 if (afrac >= 0) | |
| 66 { | |
| 67 x0 += xstep; | |
| 68 afrac -= dy; | |
| 69 } | |
| 70 | |
| 71 y0 += ystep; | |
| 72 afrac += dx; | |
| 73 | |
| 74 DM_DRAWLINE_INNER | |
| 75 } | |
| 76 } | |
| 77 | |
| 78 return 0; | |
| 79 } | |
| 80 | |
| 81 #undef DM_DRAWLINE_NAME | |
| 82 #undef DM_DRAWLINE_DST_BYTES | |
| 83 #undef DM_DRAWLINE_DST_TYPE | |
|
133
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
84 #undef DM_DRAWLINE_INIT |
|
92cc5e1fa180
Some work on line drawing routines.
Matti Hamalainen <ccr@tnsp.org>
parents:
22
diff
changeset
|
85 #undef DM_DRAWLINE_INNER |