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/* Copyright (C) 1994-2003 Revolution Software Ltd
*
* 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.
*
* $Header$
*/
#include "stdafx.h"
#include "driver/driver96.h"
#include "debug.h"
#include "defs.h"
#include "header.h"
#include "interpreter.h"
#include "layers.h"
#include "scroll.h"
// max no of pixel allowed to scroll per cycle
#define MAX_SCROLL_DISTANCE 8
// used to be a define, but now it's flexible (see new functions below)
uint8 scroll_fraction = 16;
void Set_scrolling(void) {
// 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
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
if (SCROLL_X || SCROLL_Y) {
// ensure not too far right
if (this_screen.max_scroll_offset_x > SCROLL_X)
this_screen.scroll_offset_x = SCROLL_X;
else
this_screen.scroll_offset_x = this_screen.max_scroll_offset_x;
// ensure not too far down
if (this_screen.max_scroll_offset_y > SCROLL_Y)
this_screen.scroll_offset_y = SCROLL_Y;
else
this_screen.scroll_offset_y = this_screen.max_scroll_offset_y;
} else {
// George's offset from the centre - the desired position
// for him
offset_x = this_screen.player_feet_x - this_screen.feet_x;
offset_y = this_screen.player_feet_y - this_screen.feet_y;
// prevent scrolling too far left/right/up/down
if (offset_x < 0)
offset_x = 0;
else if ((uint32) offset_x > this_screen.max_scroll_offset_x)
offset_x = this_screen.max_scroll_offset_x;
if (offset_y < 0)
offset_y = 0;
else if ((uint32) offset_y > this_screen.max_scroll_offset_y)
offset_y = this_screen.max_scroll_offset_y;
// first time on this screen - need absolute scroll
// immediately!
if (this_screen.scroll_flag == 2) {
debug(5, "init scroll");
this_screen.scroll_offset_x = offset_x;
this_screen.scroll_offset_y = offset_y;
this_screen.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)
dx = this_screen.scroll_offset_x - offset_x;
dy = this_screen.scroll_offset_y - offset_y;
// current scroll_offset_x is less than the required
// value
// NB. I'm adding 1 to the result of
// dx / SCROLL_FRACTION, because it would otherwise
// not scroll at all when dx < SCROLL_FRACTION
if (dx < 0) {
// => inc by (fraction of the differnce)
// NB. dx is -ve, so we subtract
// dx / SCROLL_FRACTION
scroll_distance_x = 1 - dx / scroll_fraction;
if (scroll_distance_x > MAX_SCROLL_DISTANCE)
scroll_distance_x = MAX_SCROLL_DISTANCE;
this_screen.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)
scroll_distance_x = 1 + dx / scroll_fraction;
if (scroll_distance_x > MAX_SCROLL_DISTANCE)
scroll_distance_x = MAX_SCROLL_DISTANCE;
this_screen.scroll_offset_x -= scroll_distance_x;
}
if (dy < 0) {
scroll_distance_y = 1 - dy / scroll_fraction;
if (scroll_distance_y > MAX_SCROLL_DISTANCE)
scroll_distance_y = MAX_SCROLL_DISTANCE;
this_screen.scroll_offset_y += scroll_distance_y;
} else if (dy > 0) {
scroll_distance_y = 1 + dy / scroll_fraction;
if (scroll_distance_y > MAX_SCROLL_DISTANCE)
scroll_distance_y = MAX_SCROLL_DISTANCE;
this_screen.scroll_offset_y -= scroll_distance_y;
}
}
}
}
int32 FN_set_scroll_coordinate(int32 *params) {
// set the special scroll offset variables
// call when starting screens and to change the camera within screens
// call AFTER FN_init_background() to override the defaults
// called feet_x and feet_y to retain intelectual compatibility with
// Sword1 !
// feet_x & feet_y refer to the physical screen coords where the
// system will try to maintain George's feet
// params: 0 feet_x value
// 1 feet_y value
this_screen.feet_x = params[0];
this_screen.feet_y = params[1];
return IR_CONT;
}
int32 FN_set_scroll_speed_normal(int32 *params) {
scroll_fraction = 16;
return IR_CONT;
}
int32 FN_set_scroll_speed_slow(int32 *params) {
scroll_fraction = 32;
return IR_CONT;
}
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