diff options
Diffstat (limited to 'sword2/scroll.cpp')
| -rw-r--r-- | sword2/scroll.cpp | 168 |
1 files changed, 85 insertions, 83 deletions
diff --git a/sword2/scroll.cpp b/sword2/scroll.cpp index 45be9a939a..82d2bdcd22 100644 --- a/sword2/scroll.cpp +++ b/sword2/scroll.cpp @@ -22,134 +22,136 @@ #include "sword2/defs.h" #include "sword2/interpreter.h" #include "sword2/logic.h" -#include "sword2/resman.h" namespace Sword2 { -// max no of pixel allowed to scroll per cycle +// Max no of pixel allowed to scroll per cycle #define MAX_SCROLL_DISTANCE 8 +/** + * If the room is larger than the physical screen, this function is called + * every game cycle to update the scroll offsets. + */ + void Sword2Engine::setScrolling(void) { - // normally we aim to get George's feet at (320,250) from top left + // Normally we aim to get George's feet at (320,250) from top left // of screen window // feet_x = 128 + 320 // feet_y = 128 + 250 - // set scroll offsets according to the player's coords + // Set scroll offsets according to the player's coords - int16 offset_x; - int16 offset_y; - int16 dx, dy; - uint16 scroll_distance_x; // how much we want to scroll - uint16 scroll_distance_y; + // If the scroll offsets are being forced in script, ensure that they + // are neither too far to the right nor too far down. - // if the scroll offsets are being forced in script if (Logic::_scriptVars[SCROLL_X] || Logic::_scriptVars[SCROLL_Y]) { - // ensure not too far right or too far down _thisScreen.scroll_offset_x = MIN((uint16) Logic::_scriptVars[SCROLL_X], _thisScreen.max_scroll_offset_x); _thisScreen.scroll_offset_y = MIN((uint16) Logic::_scriptVars[SCROLL_Y], _thisScreen.max_scroll_offset_y); - } else { - // George's offset from the centre - the desired position - // for him - - offset_x = _thisScreen.player_feet_x - _thisScreen.feet_x; - offset_y = _thisScreen.player_feet_y - _thisScreen.feet_y; + return; + } - // prevent scrolling too far left/right/up/down + // George's offset from the centre - the desired position for him - if (offset_x < 0) - offset_x = 0; - else if ((uint32) offset_x > _thisScreen.max_scroll_offset_x) - offset_x = _thisScreen.max_scroll_offset_x; + int16 offset_x = _thisScreen.player_feet_x - _thisScreen.feet_x; + int16 offset_y = _thisScreen.player_feet_y - _thisScreen.feet_y; - if (offset_y < 0) - offset_y = 0; - else if ((uint32) offset_y > _thisScreen.max_scroll_offset_y) - offset_y = _thisScreen.max_scroll_offset_y; + // Prevent scrolling too far left/right/up/down - // first time on this screen - need absolute scroll - // immediately! + if (offset_x < 0) + offset_x = 0; + else if (offset_x > _thisScreen.max_scroll_offset_x) + offset_x = _thisScreen.max_scroll_offset_x; - if (_thisScreen.scroll_flag == 2) { - debug(5, "init scroll"); - _thisScreen.scroll_offset_x = offset_x; - _thisScreen.scroll_offset_y = offset_y; - _thisScreen.scroll_flag = 1; - } else { - // catch up with required scroll offsets - speed - // depending on distance to catch up (dx and dy) & - // 'SCROLL_FRACTION' used, but limit to certain - // number of pixels per cycle (MAX_SCROLL_DISTANCE) + if (offset_y < 0) + offset_y = 0; + else if (offset_y > _thisScreen.max_scroll_offset_y) + offset_y = _thisScreen.max_scroll_offset_y; - dx = _thisScreen.scroll_offset_x - offset_x; - dy = _thisScreen.scroll_offset_y - offset_y; + // First time on this screen - need absolute scroll immediately! - // current scroll_offset_x is less than the required - // value + if (_thisScreen.scroll_flag == 2) { + debug(5, "init scroll"); + _thisScreen.scroll_offset_x = offset_x; + _thisScreen.scroll_offset_y = offset_y; + _thisScreen.scroll_flag = 1; + return; + } - // NB. I'm adding 1 to the result of - // dx / SCROLL_FRACTION, because it would otherwise - // not scroll at all when dx < SCROLL_FRACTION + // Catch up with required scroll offsets - speed depending on distance + // to catch up (dx and dy) and _scrollFraction used, but limit to + // certain number of pixels per cycle (MAX_SCROLL_DISTANCE) - if (dx < 0) { - // => inc by (fraction of the differnce) - // NB. dx is -ve, so we subtract - // dx / SCROLL_FRACTION + int16 dx = _thisScreen.scroll_offset_x - offset_x; + int16 dy = _thisScreen.scroll_offset_y - offset_y; - scroll_distance_x = 1 - dx / _scrollFraction; + uint16 scroll_distance_x; // how much we want to scroll + uint16 scroll_distance_y; - if (scroll_distance_x > MAX_SCROLL_DISTANCE) - scroll_distance_x = MAX_SCROLL_DISTANCE; + if (dx < 0) { + // Current scroll_offset_x is less than the required value - _thisScreen.scroll_offset_x += scroll_distance_x; - } else if (dx > 0) { - // current scroll_offset_x is greater than - // the required value - // => dec by (fraction of the differnce) + // NB. I'm adding 1 to the result of dx / SCROLL_FRACTION, + // because it would otherwise not scroll at all when + // dx < SCROLL_FRACTION - scroll_distance_x = 1 + dx / _scrollFraction; + // => inc by (fraction of the differnce) NB. dx is -ve, so we + // subtract dx / SCROLL_FRACTION - if (scroll_distance_x > MAX_SCROLL_DISTANCE) - scroll_distance_x = MAX_SCROLL_DISTANCE; + scroll_distance_x = 1 - dx / _scrollFraction; - _thisScreen.scroll_offset_x -= scroll_distance_x; - } + if (scroll_distance_x > MAX_SCROLL_DISTANCE) + scroll_distance_x = MAX_SCROLL_DISTANCE; - if (dy < 0) { - scroll_distance_y = 1 - dy / _scrollFraction; + _thisScreen.scroll_offset_x += scroll_distance_x; + } else if (dx > 0) { + // Current scroll_offset_x is greater than + // the required value - if (scroll_distance_y > MAX_SCROLL_DISTANCE) - scroll_distance_y = MAX_SCROLL_DISTANCE; + // => dec by (fraction of the differnce) - _thisScreen.scroll_offset_y += scroll_distance_y; - } else if (dy > 0) { - scroll_distance_y = 1 + dy / _scrollFraction; + scroll_distance_x = 1 + dx / _scrollFraction; - if (scroll_distance_y > MAX_SCROLL_DISTANCE) - scroll_distance_y = MAX_SCROLL_DISTANCE; + if (scroll_distance_x > MAX_SCROLL_DISTANCE) + scroll_distance_x = MAX_SCROLL_DISTANCE; - _thisScreen.scroll_offset_y -= scroll_distance_y; - } - } + _thisScreen.scroll_offset_x -= scroll_distance_x; } -} -int32 Logic::fnSetScrollCoordinate(int32 *params) { - // set the special scroll offset variables + if (dy < 0) { + scroll_distance_y = 1 - dy / _scrollFraction; - // call when starting screens and to change the camera within screens + if (scroll_distance_y > MAX_SCROLL_DISTANCE) + scroll_distance_y = MAX_SCROLL_DISTANCE; - // call AFTER fnInitBackground() to override the defaults + _thisScreen.scroll_offset_y += scroll_distance_y; + } else if (dy > 0) { + scroll_distance_y = 1 + dy / _scrollFraction; - // called feet_x and feet_y to retain intelectual compatibility with - // Sword1 ! + if (scroll_distance_y > MAX_SCROLL_DISTANCE) + scroll_distance_y = MAX_SCROLL_DISTANCE; - // feet_x & feet_y refer to the physical screen coords where the - // system will try to maintain George's feet + _thisScreen.scroll_offset_y -= scroll_distance_y; + } +} +/** + * Set the special scroll offset variables + * + * Call when starting screens and to change the camera within screens + * + * call AFTER fnInitBackground() to override the defaults + */ + +int32 Logic::fnSetScrollCoordinate(int32 *params) { // params: 0 feet_x value // 1 feet_y value + // Called feet_x and feet_y to retain intellectual compatibility with + // Sword1! + // + // feet_x & feet_y refer to the physical screen coords where the + // system will try to maintain George's feet + _vm->_thisScreen.feet_x = params[0]; _vm->_thisScreen.feet_y = params[1]; return IR_CONT; |