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Draw actors as they cross the viewport boundary too

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This commit is contained in:
Eevee (Evelyn Woods) 2020-09-09 20:54:19 -06:00
parent e85a896f5c
commit 57ee13425e
1 changed files with 14 additions and 3 deletions
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17
js/renderer-canvas.js
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@ -64,6 +64,7 @@ export class CanvasRenderer {
else {
[px, py] = [0, 0];
}
// Figure out where to start drawing
let x0 = Math.max(0, Math.min(this.level.size_x - this.viewport_size_x, px - xmargin));
let y0 = Math.max(0, Math.min(this.level.size_y - this.viewport_size_y, py - ymargin));
// Round to the pixel grid
@ -71,11 +72,21 @@ export class CanvasRenderer {
y0 = Math.floor(y0 * this.tileset.size_y + 0.5) / this.tileset.size_y;
this.viewport_x = x0;
this.viewport_y = y0;
// The viewport might not be aligned to the grid, so split off any fraction
// The viewport might not be aligned to the grid, so split off any fractional part.
let xf0 = Math.floor(x0);
let yf0 = Math.floor(y0);
let x1 = Math.ceil(x0 + this.viewport_size_x - 1);
let y1 = Math.ceil(y0 + this.viewport_size_y - 1);
// Note that when the viewport is exactly aligned to the grid, we need to draw the cells
// just outside of it, or we'll miss objects partway through crossing the border
if (xf0 === x0) {
xf0 -= 1;
}
if (yf0 === y0) {
yf0 -= 1;
}
// Find where to stop drawing. As with above, if we're aligned to the grid, we need to
// include the tiles just outside it, so we allow this fencepost problem to fly
let x1 = Math.ceil(x0 + this.viewport_size_x);
let y1 = Math.ceil(y0 + this.viewport_size_y);
// Draw one layer at a time, so animated objects aren't overdrawn by
// neighboring terrain
// XXX layer count hardcoded here