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Diffstat (limited to 'src/uqm/planets/gentopo.c')
| -rw-r--r-- | src/uqm/planets/gentopo.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/src/uqm/planets/gentopo.c b/src/uqm/planets/gentopo.c new file mode 100644 index 0000000..5212143 --- /dev/null +++ b/src/uqm/planets/gentopo.c @@ -0,0 +1,206 @@ +//Copyright Paul Reiche, Fred Ford. 1992-2002 + +/* + * This program 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. + * + * This program 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 this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ + +// See doc/devel/planettopo for details. + +#include "libs/gfxlib.h" +#include "libs/mathlib.h" +#include "planets.h" + +void +DeltaTopography (COUNT num_iterations, SBYTE *DepthArray, RECT *pRect, + SIZE depth_delta) +{ + SIZE width, height, delta_y; + struct + { + COORD x_top, x_bot; + SIZE x_incr, delta_x, error_term; + } LineDDA0, LineDDA1; + + width = pRect->extent.width; + height = pRect->extent.height; + delta_y = (height - 1) << 1; + do + { + SIZE d; + COUNT h, w1, w2; + DWORD rand_val; + SBYTE *lpDst; + + if ((RandomContext_Random (SysGenRNG) & 1) == 0) + depth_delta = -depth_delta; + + rand_val = RandomContext_Random (SysGenRNG); + w1 = LOWORD (rand_val); + w2 = HIWORD (rand_val); + + LineDDA0.x_top = LOBYTE (w1) % width; + LineDDA0.x_bot = HIBYTE (w1) % width; + LineDDA0.delta_x = (LineDDA0.x_bot - LineDDA0.x_top) << 1; + if (LineDDA0.delta_x >= 0) + LineDDA0.x_incr = 1; + else + { + LineDDA0.x_incr = -1; + LineDDA0.delta_x = -LineDDA0.delta_x; + } + if (LineDDA0.delta_x > delta_y) + LineDDA0.error_term = -(LineDDA0.delta_x >> 1); + else + LineDDA0.error_term = -(delta_y >> 1); + + LineDDA1.x_top = (LOBYTE (w2) % (width - 1)) + LineDDA0.x_top + 1; + LineDDA1.x_bot = (HIBYTE (w2) % (width - 1)) + LineDDA0.x_bot + 1; + LineDDA1.delta_x = (LineDDA1.x_bot - LineDDA1.x_top) << 1; + if (LineDDA1.delta_x >= 0) + LineDDA1.x_incr = 1; + else + { + LineDDA1.x_incr = -1; + LineDDA1.delta_x = -LineDDA1.delta_x; + } + if (LineDDA1.delta_x > delta_y) + LineDDA1.error_term = -(LineDDA1.delta_x >> 1); + else + LineDDA1.error_term = -(delta_y >> 1); + + lpDst = &DepthArray[LineDDA0.x_top]; + h = height; + do + { + COUNT w; + + w1 = LineDDA1.x_top - LineDDA0.x_top; + w2 = width - w1; + + if ((int)(LineDDA0.x_top + w1) > (int)width) + w = width - LineDDA0.x_top; + else + { + w = w1; + LineDDA0.x_top += w1; + } + w1 -= w; + while (w--) + { + d = *lpDst + depth_delta; + if (d >= -128 && d <= 127) + *lpDst = (SBYTE)d; + ++lpDst; + } + if (w1 == 0) + { + if (LineDDA0.x_top == width) + { + LineDDA0.x_top = 0; + lpDst -= width; + } + } + else + { + LineDDA0.x_top = w1; + lpDst -= width; + do + { + d = *lpDst + depth_delta; + if (d >= -128 && d <= 127) + *lpDst = (SBYTE)d; + ++lpDst; + } while (--w1); + } + + if ((int)(LineDDA0.x_top + w2) > (int)width) + w = width - LineDDA0.x_top; + else + { + w = w2; + LineDDA0.x_top += w2; + } + w2 -= w; + while (w--) + { + d = *lpDst - depth_delta; + if (d >= -128 && d <= 127) + *lpDst = (SBYTE)d; + ++lpDst; + } + if (w2 == 0) + { + if (LineDDA0.x_top == width) + { + LineDDA0.x_top = 0; + lpDst -= width; + } + } + else + { + LineDDA0.x_top = w2; + lpDst -= width; + do + { + d = *lpDst - depth_delta; + if (d >= -128 && d <= 127) + *lpDst = (SBYTE)d; + ++lpDst; + } while (--w2); + } + + lpDst += pRect->extent.width; + + if (delta_y >= LineDDA0.delta_x) + { + if ((LineDDA0.error_term += LineDDA0.delta_x) >= 0) + { + lpDst += LineDDA0.x_incr; + LineDDA0.x_top += LineDDA0.x_incr; + LineDDA0.error_term -= delta_y; + } + } + else + { + do + { + lpDst += LineDDA0.x_incr; + LineDDA0.x_top += LineDDA0.x_incr; + } while ((LineDDA0.error_term += delta_y) < 0); + LineDDA0.error_term -= LineDDA0.delta_x; + } + + if (delta_y >= LineDDA1.delta_x) + { + if ((LineDDA1.error_term += LineDDA1.delta_x) >= 0) + { + LineDDA1.x_top += LineDDA1.x_incr; + LineDDA1.error_term -= delta_y; + } + } + else + { + do + { + LineDDA1.x_top += LineDDA1.x_incr; + } while ((LineDDA1.error_term += delta_y) < 0); + LineDDA1.error_term -= LineDDA1.delta_x; + } + } while (--h); + } while (--num_iterations); +} + + + |