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Fix: jumping effect when scrolling viewport over bottom edge of the map (Patch by adf88, #6583)

This commit is contained in:
Johannes E. Krause 2019-01-13 20:54:21 +01:00 committed by Niels Martin Hansen
parent f0290d5de7
commit f744dea0ff
3 changed files with 33 additions and 114 deletions
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9
src/landscape.cpp
View File

@ -96,13 +96,16 @@ static SnowLine *_snow_line = NULL;
* @param x X viewport 2D coordinate.
* @param y Y viewport 2D coordinate.
* @param clamp_to_map Clamp the coordinate outside of the map to the closest, non-void tile within the map.
* @param[out] clamped Whether coordinates were clamped.
* @return 3D world coordinate of point visible at the given screen coordinate (3D perspective).
*
* @note Inverse of #RemapCoords2 function. Smaller values may get rounded.
* @see InverseRemapCoords
*/
Point InverseRemapCoords2(int x, int y, bool clamp_to_map)
Point InverseRemapCoords2(int x, int y, bool clamp_to_map, bool *clamped)
{
if (clamped != NULL) *clamped = false; // Not clamping yet.
/* Initial x/y world coordinate is like if the landscape
* was completely flat on height 0. */
Point pt = InverseRemapCoords(x, y);
@ -116,8 +119,10 @@ Point InverseRemapCoords2(int x, int y, bool clamp_to_map)
* of extra tiles. This is mostly due to the tiles on the north side of
* the map possibly being drawn higher due to the extra height levels. */
int extra_tiles = CeilDiv(_settings_game.construction.max_heightlevel * TILE_HEIGHT, TILE_PIXELS);
Point old_pt = pt;
pt.x = Clamp(pt.x, -extra_tiles * TILE_SIZE, max_x);
pt.y = Clamp(pt.y, -extra_tiles * TILE_SIZE, max_y);
if (clamped != NULL) *clamped = (pt.x != old_pt.x) || (pt.y != old_pt.y);
}
/* Now find the Z-world coordinate by fix point iteration.
@ -133,8 +138,10 @@ Point InverseRemapCoords2(int x, int y, bool clamp_to_map)
pt.x += z;
pt.y += z;
if (clamp_to_map) {
Point old_pt = pt;
pt.x = Clamp(pt.x, min_coord, max_x);
pt.y = Clamp(pt.y, min_coord, max_y);
if (clamped != NULL) *clamped = *clamped || (pt.x != old_pt.x) || (pt.y != old_pt.y);
}
return pt;

2
src/landscape.h
View File

@ -116,7 +116,7 @@ static inline Point InverseRemapCoords(int x, int y)
return pt;
}
Point InverseRemapCoords2(int x, int y, bool clamp_to_map = false);
Point InverseRemapCoords2(int x, int y, bool clamp_to_map = false, bool *clamped = NULL);
uint ApplyFoundationToSlope(Foundation f, Slope *s);
/**

136
src/viewport.cpp
View File

@ -1631,121 +1631,33 @@ void Window::DrawViewport() const
}
/**
* Continue criteria for the SearchMapEdge function.
* @param iter Value to check.
* @param iter_limit Maximum value for the iter
* @param sy Screen y coordinate calculated for the tile at hand
* @param sy_limit Limit to the screen y coordinate
* @return True when we should continue searching.
* Ensure that a given viewport has a valid scroll position.
*
* There must be a visible piece of the map in the center of the viewport.
* If there isn't, the viewport will be scrolled to nearest such location.
*
* @param vp The viewport.
* @param[in,out] scroll_x Viewport X scroll.
* @param[in,out] scroll_y Viewport Y scroll.
*/
typedef bool ContinueMapEdgeSearch(int iter, int iter_limit, int sy, int sy_limit);
/** Continue criteria for searching a no-longer-visible tile in negative direction, starting at some tile. */
static inline bool ContinueLowerMapEdgeSearch(int iter, int iter_limit, int sy, int sy_limit) { return iter > 0 && sy > sy_limit; }
/** Continue criteria for searching a no-longer-visible tile in positive direction, starting at some tile. */
static inline bool ContinueUpperMapEdgeSearch(int iter, int iter_limit, int sy, int sy_limit) { return iter < iter_limit && sy < sy_limit; }
/**
* Searches, starting at the given tile, by applying the given offset to iter, for a no longer visible tile.
* The whole sense of this function is keeping the to-be-written code small, thus it is a little bit abstracted
* so the same function can be used for both the X and Y locations. As such a reference to one of the elements
* in curr_tile was needed.
* @param curr_tile A tile
* @param iter Reference to either the X or Y of curr_tile.
* @param iter_limit Upper search limit for the iter value.
* @param offset Search in steps of this size
* @param sy_limit Search limit to be passed to the criteria
* @param continue_criteria Search as long as this criteria is true
* @return The final value of iter.
*/
static int SearchMapEdge(Point &curr_tile, int &iter, int iter_limit, int offset, int sy_limit, ContinueMapEdgeSearch continue_criteria)
static inline void ClampViewportToMap(const ViewPort *vp, int *scroll_x, int *scroll_y)
{
int sy;
do {
iter = Clamp(iter + offset, 0, iter_limit);
sy = GetViewportY(curr_tile);
} while (continue_criteria(iter, iter_limit, sy, sy_limit));
/* Centre of the viewport is hot spot. */
Point pt = {
*scroll_x + vp->virtual_width / 2,
*scroll_y + vp->virtual_height / 2
};
return iter;
}
/* Find nearest tile that is within borders of the map. */
bool clamped;
pt = InverseRemapCoords2(pt.x, pt.y, true, &clamped);
/**
* Determine the clamping of either the X or Y coordinate to the map.
* @param curr_tile A tile
* @param iter Reference to either the X or Y of curr_tile.
* @param iter_limit Upper search limit for the iter value.
* @param start Start value for the iteration.
* @param other_ref Reference to the opposite axis in curr_tile than of iter.
* @param other_value Start value for of the opposite axis
* @param vp_value Value of the viewport location in the opposite axis as for iter.
* @param other_limit Limit for the other value, so if iter is X, then other_limit is for Y.
* @param vp_top Top of the viewport.
* @param vp_bottom Bottom of the viewport.
* @return Clamped version of vp_value.
*/
static inline int ClampXYToMap(Point &curr_tile, int &iter, int iter_limit, int start, int &other_ref, int other_value, int vp_value, int other_limit, int vp_top, int vp_bottom)
{
bool upper_edge = other_value < _settings_game.construction.max_heightlevel / 4;
/*
* First get an estimate of the tiles relevant for us at that edge. Relevant in the sense
* "at least close to the visible area". Thus, we don't look at exactly each tile, inspecting
* e.g. every tenth should be enough. After all, the desired screen limit is set such that
* the bordermost tiles are painted in the middle of the screen when one hits the limit,
* i.e. it is no harm if there is some small error in that calculation
*/
other_ref = upper_edge ? 0 : other_limit;
iter = start;
int min_iter = SearchMapEdge(curr_tile, iter, iter_limit, upper_edge ? -10 : +10, vp_top, upper_edge ? ContinueLowerMapEdgeSearch : ContinueUpperMapEdgeSearch);
iter = start;
int max_iter = SearchMapEdge(curr_tile, iter, iter_limit, upper_edge ? +10 : -10, vp_bottom, upper_edge ? ContinueUpperMapEdgeSearch : ContinueLowerMapEdgeSearch);
max_iter = min(max_iter + _settings_game.construction.max_heightlevel / 4, iter_limit);
min_iter = min(min_iter, max_iter);
/* Now, calculate the highest heightlevel of these tiles. Again just as an estimate. */
int max_heightlevel_at_edge = 0;
for (iter = min_iter; iter <= max_iter; iter += 10) {
max_heightlevel_at_edge = max(max_heightlevel_at_edge, (int)TileHeight(TileXY(curr_tile.x, curr_tile.y)));
if (clamped) {
/* Convert back to viewport coordinates and remove centering. */
pt = RemapCoords2(pt.x, pt.y);
*scroll_x = pt.x - vp->virtual_width / 2;
*scroll_y = pt.y - vp->virtual_height / 2;
}
/* Based on that heightlevel, calculate the limit. For the upper edge a tile with height zero would
* get a limit of zero, on the other side it depends on the number of tiles along the axis. */
return upper_edge ?
max(vp_value, -max_heightlevel_at_edge * (int)(TILE_HEIGHT * 2 * ZOOM_LVL_BASE)) :
min(vp_value, (other_limit * TILE_SIZE * 4 - max_heightlevel_at_edge * TILE_HEIGHT * 2) * ZOOM_LVL_BASE);
}
static inline void ClampViewportToMap(const ViewPort *vp, int &x, int &y)
{
int original_y = y;
/* Centre of the viewport is hot spot */
x += vp->virtual_width / 2;
y += vp->virtual_height / 2;
/* Convert viewport coordinates to map coordinates
* Calculation is scaled by 4 to avoid rounding errors */
int vx = -x + y * 2;
int vy = x + y * 2;
/* Find out which tile corresponds to (vx,vy) if one assumes height zero. The cast is necessary to prevent C++ from
* converting the result to an uint, which gives an overflow instead of a negative result... */
int tx = vx / (int)(TILE_SIZE * 4 * ZOOM_LVL_BASE);
int ty = vy / (int)(TILE_SIZE * 4 * ZOOM_LVL_BASE);
Point curr_tile;
vx = ClampXYToMap(curr_tile, curr_tile.y, MapMaxY(), ty, curr_tile.x, tx, vx, MapMaxX(), original_y, original_y + vp->virtual_height);
vy = ClampXYToMap(curr_tile, curr_tile.x, MapMaxX(), tx, curr_tile.y, ty, vy, MapMaxY(), original_y, original_y + vp->virtual_height);
/* Convert map coordinates to viewport coordinates */
x = (-vx + vy) / 2;
y = ( vx + vy) / 4;
/* Remove centering */
x -= vp->virtual_width / 2;
y -= vp->virtual_height / 2;
}
/**
@ -1765,7 +1677,7 @@ void UpdateViewportPosition(Window *w)
SetViewportPosition(w, pt.x, pt.y);
} else {
/* Ensure the destination location is within the map */
ClampViewportToMap(vp, w->viewport->dest_scrollpos_x, w->viewport->dest_scrollpos_y);
ClampViewportToMap(vp, &w->viewport->dest_scrollpos_x, &w->viewport->dest_scrollpos_y);
int delta_x = w->viewport->dest_scrollpos_x - w->viewport->scrollpos_x;
int delta_y = w->viewport->dest_scrollpos_y - w->viewport->scrollpos_y;
@ -1785,7 +1697,7 @@ void UpdateViewportPosition(Window *w)
w->viewport->scrollpos_y == w->viewport->dest_scrollpos_y);
}
ClampViewportToMap(vp, w->viewport->scrollpos_x, w->viewport->scrollpos_y);
ClampViewportToMap(vp, &w->viewport->scrollpos_x, &w->viewport->scrollpos_y);
SetViewportPosition(w, w->viewport->scrollpos_x, w->viewport->scrollpos_y);
if (update_overlay) RebuildViewportOverlay(w);