Render multiple Z levels

Performance regression warning: this is now quite slow to render when showing
all 7 Z levels. Bounds clipping may be enough to get it back to acceptable
levels, or we may have to do something cleverer

cmd/view-map/main.go

@@ -112,10 +112,10 @@ func (e *env) run() {
 	})
 }
 
-func (e *env) getSprite(palette []string, ref maps.ObjRef) (*conv.Sprite, *conv.Object) {
+func (e *env) getSprite(palette []string, ref maps.ObjRef) *conv.Sprite {
 	if ref.Index() >= len(palette) {
 		log.Printf("Palette too small: %v requested", ref.Index())
-		return nil, nil
+		return nil
 	}
 
 	name := palette[ref.Index()]
@@ -123,15 +123,15 @@ func (e *env) getSprite(palette []string, ref maps.ObjRef) (*conv.Sprite, *conv.
 	obj := e.objects[name]
 	if obj == nil {
 		log.Printf("Failed to find surface sprite %#v -> %q", ref, name)
-		return nil, nil
+		return nil
 	}
 
 	if ref.Frame() >= len(obj.Sprites) {
 		log.Printf("Out-of-index sprite %v requested for %v", ref.Frame(), name)
-		return nil, obj
+		return nil
 	}
 
-	return &obj.Sprites[ref.Frame()], obj
+	return &obj.Sprites[ref.Frame()]
 }
 
 var (
@@ -142,8 +142,6 @@ var (
 // TODO: build all the sprites in the set into a single spritesheet so we can
 // use pixel.Batch
 func (s *state) present(pWin *pixelgl.Window) {
-	gameMap := s.env.gameMap
-
 	pWin.Clear(colornames.Black)
 
 	center := pWin.Bounds().Center()
@@ -156,45 +154,56 @@ func (s *state) present(pWin *pixelgl.Window) {
 	s.cam = cam
 	pWin.SetMatrix(cam)
 
-	// TODO: bounds clipping
+	// TODO: we should be able to perform bounds clipping on these
-	z := int(s.zIdx)
+	minX := int(s.env.gameMap.MinWidth)
-	for y := int(gameMap.MinLength); y < int(gameMap.MaxLength); y++ {
+	maxX := int(s.env.gameMap.MaxWidth)
-		for x := int(gameMap.MinWidth); x < int(gameMap.MaxWidth); x++ {
+	minY := int(s.env.gameMap.MinLength)
+	maxY := int(s.env.gameMap.MaxLength)
+	minZ := 0
+	maxZ := int(s.zIdx) + 1
 
-			cell := gameMap.Cells.At(x, y, z)
+	for z := minZ; z < maxZ; z++ {
+		for y := minY; y < maxY; y++ {
+			for x := minX; x < maxX; x++ {
+				s.renderCell(x, y, z, pWin)
+			}
+		}
+	}
+}
 
-			surfaceSprite, _ := s.env.getSprite(s.env.set.Palette, cell.Surface)
+func (s *state) renderCell(x, y, z int, pWin *pixelgl.Window) {
-			centerSprite, _ := s.env.getSprite(s.env.set.Palette, cell.Center)
+	var sprites []*conv.Sprite
-			leftSprite, _ := s.env.getSprite(s.env.set.Palette, cell.Left)
-			rightSprite, _ := s.env.getSprite(s.env.set.Palette, cell.Right)
 
-			fX := float64(x)
+	cell := s.env.gameMap.Cells.At(x, y, z)
-			fY := float64(y)
+
+	// Try optimizing zero surfaces out, they tend to be? all-transparent
+	if cell.Surface.Index() != 0 {
+		sprites = append(sprites, s.env.getSprite(s.env.set.Palette, cell.Surface))
+	}
+
+	sprites = append(
+		sprites,
+		s.env.getSprite(s.env.set.Palette, cell.Center),
+		s.env.getSprite(s.env.set.Palette, cell.Left),
+		s.env.getSprite(s.env.set.Palette, cell.Right),
+	)
+
+	// Taking the Z index away *seems* to draw the object in the correct place.
+	// FIXME: There are some artifacts, investigate more
+	fX := float64(x - z)
+	fY := float64(y - z)
 
 	xPos := fX * cellWidth
 	yPos := fY * cellLength
 
 	// The rotation translates the rectangular coordinates to diamond
 	// ones \o/
-			// FIXME: these are off by a bit
 	orig := pixel.V(xPos, yPos)
 	iso := pixel.V(orig.X-orig.Y, (orig.X+orig.Y)/2.0)
 
-			if surfaceSprite != nil {
+	for _, sprite := range sprites {
-				surfaceSprite.Spr.Draw(pWin, pixel.IM.Moved(iso))
+		if sprite != nil {
-			}
+			sprite.Spr.Draw(pWin, pixel.IM.Moved(iso))
-
-			if centerSprite != nil {
-				centerSprite.Spr.Draw(pWin, pixel.IM.Moved(iso))
-			}
-
-			if leftSprite != nil {
-				leftSprite.Spr.Draw(pWin, pixel.IM.Moved(iso))
-			}
-
-			if rightSprite != nil {
-				rightSprite.Spr.Draw(pWin, pixel.IM.Moved(iso))
-			}
 		}
 	}
 }