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| Rev 5218 | Rev 5278 | ||
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| 225 | ; Line Clipping algorithm from 'Computer Graphics', Principles and |
225 | ; Line Clipping algorithm from 'Computer Graphics', Principles and |
| 226 | ; Practice |
226 | ; Practice |
| 227 | ; tmin,tmax -> &float |
227 | ; tmin,tmax -> &float |
| 228 | align 4 |
228 | align 4 |
| 229 | proc ClipLine1 uses ebx, denom:dword,num:dword,tmin:dword,tmax:dword |
229 | proc ClipLine1 uses ebx, denom:dword,num:dword,tmin:dword,tmax:dword |
| 230 | fldz |
- | |
| 231 | fcom dword[denom] |
230 | fld dword[denom] |
| - | 231 | ftst |
|
| 232 | fstsw ax |
232 | fstsw ax |
| 233 | sahf |
233 | sahf |
| 234 | je .u2 |
- | |
| 235 | jmp @f |
- | |
| 236 | .u2: |
- | |
| 237 | fcom dword[num] |
- | |
| 238 | fstsw ax |
- | |
| 239 | sahf |
- | |
| 240 | jb .r0 ;if (denom==0 && num>0) return 0 |
- | |
| 241 | jmp .r1 |
- | |
| 242 | @@: |
- | |
| 243 | - | ||
| 244 | fcom dword[denom] |
- | |
| 245 | fstsw ax |
- | |
| 246 | sahf |
- | |
| 247 | ja .els_0 ;if (0 |
234 | jbe .els_0 ;if (denom>0) |
| 248 | fld dword[num] |
235 | fld dword[num] |
| - | 236 | fxch st1 |
|
| 249 | fdiv dword[denom] |
237 | fdivp ;t=num/denom |
| 250 | - | ||
| 251 | mov ebx,[tmax] |
238 | mov ebx,[tmax] |
| 252 | fcom dword[ebx] |
239 | fcom dword[ebx] |
| 253 | fstsw ax |
240 | fstsw ax |
| 254 | sahf |
241 | sahf |
| 255 | ja .r0_f2 ;if (t>*tmax) return 0 |
242 | ja .r0_f1 ;if (t>*tmax) return 0 |
| 256 | - | ||
| 257 | mov ebx,[tmin] |
243 | mov ebx,[tmin] |
| 258 | fcom dword[ebx] |
244 | fcom dword[ebx] |
| 259 | fstsw ax |
245 | fstsw ax |
| 260 | sahf |
246 | sahf |
| 261 | jbe .r1_f2 |
247 | jbe .r1_f1 ;if (t>*tmin) *tmin=t |
| 262 | fstp dword[ebx] ;if (t>*tmin) *tmin=t |
248 | fstp dword[ebx] |
| 263 | jmp .r1 |
249 | jmp .r1 |
| 264 | - | ||
| 265 | .els_0: ;else if (0>denom) |
250 | .els_0: ;else if (denom<0) |
| - | 251 | jae .els_1 |
|
| 266 | fld dword[num] |
252 | fld dword[num] |
| - | 253 | fxch st1 |
|
| 267 | fdiv dword[denom] |
254 | fdivp ;t=num/denom |
| 268 | - | ||
| 269 | mov ebx,[tmin] |
255 | mov ebx,[tmin] |
| 270 | fcom dword[ebx] |
256 | fcom dword[ebx] |
| 271 | fstsw ax |
257 | fstsw ax |
| 272 | sahf |
258 | sahf |
| 273 | jb .r0_f2 ;if (t<*tmin) return 0 |
259 | jb .r0_f1 ;if (t<*tmin) return 0 |
| 274 | - | ||
| 275 | mov ebx,[tmax] |
260 | mov ebx,[tmax] |
| 276 | fcom dword[ebx] |
261 | fcom dword[ebx] |
| 277 | fstsw ax |
262 | fstsw ax |
| 278 | sahf |
263 | sahf |
| 279 | jae .r1_f2 |
264 | jae .r1_f1 |
| 280 | fstp dword[ebx] ;if (t<*tmin) *tmax=t |
265 | fstp dword[ebx] ;if (t<*tmin) *tmax=t |
| 281 | jmp .r1 |
266 | jmp .r1 |
| - | 267 | .els_1: ;else if (num>0) |
|
| - | 268 | ffree st0 ;denom |
|
| - | 269 | fincstp |
|
| - | 270 | fld dword[num] |
|
| - | 271 | ftst |
|
| - | 272 | fstsw ax |
|
| - | 273 | sahf |
|
| - | 274 | ja .r0_f1 ;if (num>0) return 0 |
|
| - | 275 | jmp .r1_f1 |
|
| Line 282... | Line 276... | ||
| 282 | 276 | ||
| 283 | .r0_f2: ;return 0 & free st0,st1 |
277 | .r0_f1: ;return 0 & free st0 |
| 284 | ffree st0 |
278 | ffree st0 |
| 285 | fincstp |
279 | fincstp |
| 286 | .r0: ;return 0 & free st0 |
280 | .r0: ;return 0 |
| 287 | xor eax,eax |
281 | xor eax,eax |
| 288 | jmp .end_f |
282 | jmp .end_f |
| 289 | .r1_f2: ;return 1 & free st0,st1 |
283 | .r1_f1: ;return 1 & free st0 |
| 290 | ffree st0 |
284 | ffree st0 |
| 291 | fincstp |
285 | fincstp |
| 292 | .r1: ;return 1 & free st0 |
286 | .r1: ;return 1 |
| 293 | xor eax,eax |
287 | xor eax,eax |
| 294 | inc eax |
288 | inc eax |
| 295 | .end_f: |
- | |
| 296 | ffree st0 |
- | |
| 297 | fincstp |
289 | .end_f: |
| 298 | ret |
290 | ret |
| Line 299... | Line 291... | ||
| 299 | endp |
291 | endp |
| 300 | 292 | ||