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comparison src/haptic/linux/SDL_syshaptic.c @ 3680:7c18b38f0f9a

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Fixed bug #920 From Martin: Alright... I corrected SDL_SYS_ToDirection in SDL_syshaptic.c in the linux directory of haptic. Now in all 3 cases the same value is returned, at least. Therefore now it should behave the same way as on Windows. I added some comments and corrected the cases SDL_HAPTIC_CARTESIAN and SDL_HAPTIC_SPHERICAL.
author Sam Lantinga <slouken@libsdl.org>
date Mon, 18 Jan 2010 14:57:41 +0000
parents 81773a1eac83
children 0c71708adbcb
comparison
equal deleted inserted replaced
3679:ce290de32f2a 3680:7c18b38f0f9a
503 Uint32 tmp; 503 Uint32 tmp;
504 float f; /* Ideally we'd use fixed point math instead of floats... */ 504 float f; /* Ideally we'd use fixed point math instead of floats... */
505 505
506 switch (dir->type) { 506 switch (dir->type) {
507 case SDL_HAPTIC_POLAR: 507 case SDL_HAPTIC_POLAR:
508 /* Linux directions are inverted. */ 508 /* Linux directions start from south.
509 tmp = (((18000 + dir->dir[0]) % 36000) * 0xFFFF) / 36000; 509 (and range from 0 to 0xFFFF)
510 Quoting include/linux/input.h, line 926:
511 Direction of the effect is encoded as follows:
512 0 deg -> 0x0000 (down)
513 90 deg -> 0x4000 (left)
514 180 deg -> 0x8000 (up)
515 270 deg -> 0xC000 (right)
516 */
517 tmp = (((18000 + dir->dir[0]) % 36000) * 0xFFFF) / 36000; // convert to range [0,0xFFFF]
510 return (Uint16) tmp; 518 return (Uint16) tmp;
511 519
520 case SDL_HAPTIC_SPHERICAL:
521 /*
522 We convert to polar, because that's the only supported direction on Linux.
523 The first value of a spherical direction is practically the same as a
524 Polar direction, except that we have to add 90 degrees. It is the angle
525 from EAST {1,0} towards SOUTH {0,1}.
526 --> add 9000
527 --> finally add 18000 and convert to [0,0xFFFF] as in case SDL_HAPTIC_POLAR.
528 */
529 tmp = ((dir->dir[0]) + 9000) % 36000; /* Convert to polars */
530 tmp = (((18000 + tmp) % 36000) * 0xFFFF) / 36000; // convert to range [0,0xFFFF]
531 return (Uint16) tmp;
532
512 case SDL_HAPTIC_CARTESIAN: 533 case SDL_HAPTIC_CARTESIAN:
513 /* We must invert "x" and "y" to go clockwise. */ 534 f = atan2(dir->dir[1], dir->dir[0]);
514 f = atan2(dir->dir[0], dir->dir[1]); 535 /*
515 tmp = (int) (f * 18000. / M_PI) % 36000; 536 atan2 takes the parameters: Y-axis-value and X-axis-value (in that order)
516 tmp = (tmp * 0xFFFF) / 36000; 537 - Y-axis-value is the second coordinate (from center to SOUTH)
517 return (Uint16) tmp; 538 - X-axis-value is the first coordinate (from center to EAST)
518 539 We add 36000, because atan2 also returns negative values. Then we practically
519 case SDL_HAPTIC_SPHERICAL: 540 have the first spherical value. Therefore we proceed as in case
520 tmp = (36000 - dir->dir[0]) + 27000; /* Convert to polars */ 541 SDL_HAPTIC_SPHERICAL and add another 9000 to get the polar value.
521 tmp = (((18000 + tmp) % 36000) * 0xFFFF) / 36000; 542 --> add 45000 in total
543 --> finally add 18000 and convert to [0,0xFFFF] as in case SDL_HAPTIC_POLAR.
544 */
545 tmp = (((int) (f * 18000. / M_PI)) + 45000) % 36000;
546 tmp = (((18000 + tmp) % 36000) * 0xFFFF) / 36000; // convert to range [0,0xFFFF]
522 return (Uint16) tmp; 547 return (Uint16) tmp;
523 548
524 default: 549 default:
525 SDL_SetError("Haptic: Unsupported direction type."); 550 SDL_SetError("Haptic: Unsupported direction type.");
526 return (Uint16) - 1; 551 return (Uint16) - 1;