draw optimizations

client/world/renderer_draw_primitives.go

@@ -1,5 +1,12 @@
 package world
 
+// lineSeg is one canonical segment (endpoints in [0..W) x [0..H)) to be drawn.
+// It represents part of the torus-shortest polyline for a Line primitive after wrap splitting.
+type lineSeg struct {
+	x1, y1 int
+	x2, y2 int
+}
+
 // drawPointInTile draws point marker copies that intersect the tile.
 // lastStyle is already applied; it provides PointRadiusPx.
 func (w *World) drawPointInTile(drawer PrimitiveDrawer, plan RenderPlan, td TileDrawPlan, p Point, allowWrap bool, lastStyle Style) {
@@ -46,9 +53,11 @@ func (w *World) drawCircleInTile(drawer PrimitiveDrawer, plan RenderPlan, td Til
 	var shifts []wrapShift
 	effRadius := circleRadiusEffFp(c.Radius, w.circleRadiusScaleFp)
 	if allowWrap {
-		shifts = circleWrapShifts(c.X, c.Y, effRadius, w.W, w.H)
+		shifts = circleWrapShiftsInto(w.scratchWrapShifts, c.X, c.Y, effRadius, w.W, w.H)
 	} else {
-		shifts = []wrapShift{{dx: 0, dy: 0}}
+		var one [1]wrapShift
+		one[0] = wrapShift{dx: 0, dy: 0}
+		shifts = one[:]
 	}
 
 	rPx := worldSpanFixedToCanvasPx(effRadius, plan.ZoomFp)
@@ -61,37 +70,68 @@ func (w *World) drawCircleInTile(drawer PrimitiveDrawer, plan RenderPlan, td Til
 		cxPx := worldSpanFixedToCanvasPx((c.X+td.Tile.OffsetX+s.dx)-plan.WorldRect.minX, plan.ZoomFp)
 		cyPx := worldSpanFixedToCanvasPx((c.Y+td.Tile.OffsetY+s.dy)-plan.WorldRect.minY, plan.ZoomFp)
 
-		drawer.AddCircle(float64(cxPx), float64(cyPx), float64(rPx))
-
 		fill := alphaNonZero(lastStyle.FillColor)
 		stroke := alphaNonZero(lastStyle.StrokeColor)
 
-		if fill {
+		switch {
+		case fill && stroke:
+			// gg consumes the current path on Fill/Stroke, so we must draw twice:
+			// once for fill, then again for stroke.
+			drawer.AddCircle(float64(cxPx), float64(cyPx), float64(rPx))
 			drawer.Fill()
-		}
-		if stroke {
-			// Stroke must be last when both are present.
+
+			drawer.AddCircle(float64(cxPx), float64(cyPx), float64(rPx))
 			drawer.Stroke()
+
+		case fill:
+			drawer.AddCircle(float64(cxPx), float64(cyPx), float64(rPx))
+			drawer.Fill()
+
+		case stroke:
+			drawer.AddCircle(float64(cxPx), float64(cyPx), float64(rPx))
+			drawer.Stroke()
+
+		default:
+			// neither visible => nothing
 		}
 	}
+	w.scratchWrapShifts = shifts[:0]
 }
 
-func (w *World) drawLineInTile(drawer PrimitiveDrawer, plan RenderPlan, td TileDrawPlan, l Line, allowWrap bool) {
-	var segs []lineSeg
+func (w *World) drawLineInTilePath(drawer PrimitiveDrawer, plan RenderPlan, td TileDrawPlan, l Line, allowWrap bool) int {
+	segs := w.scratchLineSegs[:0]
+	tmp := w.scratchLineSegsTmp[:0]
+	if cap(segs) < 4 {
+		segs = make([]lineSeg, 0, 4)
+	}
+	if cap(tmp) < 4 {
+		tmp = make([]lineSeg, 0, 4)
+	}
+
 	if allowWrap {
-		segs = torusShortestLineSegments(l, w.W, w.H)
+		segs, tmp = torusShortestLineSegmentsInto(segs, tmp, l, w.W, w.H)
 	} else {
-		segs = []lineSeg{{x1: l.X1, y1: l.Y1, x2: l.X2, y2: l.Y2}}
+		var one [1]lineSeg
+		one[0] = lineSeg{x1: l.X1, y1: l.Y1, x2: l.X2, y2: l.Y2}
+		segs = one[:]
 	}
 
 	for _, s := range segs {
-		// Project into tile/canvas.
 		x1 := worldSpanFixedToCanvasPx((s.x1+td.Tile.OffsetX)-plan.WorldRect.minX, plan.ZoomFp)
 		y1 := worldSpanFixedToCanvasPx((s.y1+td.Tile.OffsetY)-plan.WorldRect.minY, plan.ZoomFp)
 		x2 := worldSpanFixedToCanvasPx((s.x2+td.Tile.OffsetX)-plan.WorldRect.minX, plan.ZoomFp)
 		y2 := worldSpanFixedToCanvasPx((s.y2+td.Tile.OffsetY)-plan.WorldRect.minY, plan.ZoomFp)
 
 		drawer.AddLine(float64(x1), float64(y1), float64(x2), float64(y2))
-		drawer.Stroke()
 	}
+
+	w.scratchLineSegs = segs[:0]
+	w.scratchLineSegsTmp = tmp[:0]
+
+	return len(segs)
+}
+
+func (w *World) drawLineInTile(drawer PrimitiveDrawer, plan RenderPlan, td TileDrawPlan, l Line, allowWrap bool) {
+	w.drawLineInTilePath(drawer, plan, td, l, allowWrap)
+	drawer.Stroke()
 }