Added IsometricProjection.

play/isometricprojection.go

@@ -0,0 +1,158 @@
+package play
+
+import (
+	"opslag.de/schobers/geom"
+)
+
+// IsometricProjection represents an 2D area (view) that contains isometric tiles.
+type IsometricProjection struct {
+	center      geom.PointF32 // tile coordinate
+	zoom        float32       // factor a tile is blown up (negative is smaller, possitive is larger)
+	zoomInverse float32       // 1/zoom; calculated
+
+	tileSize   geom.PointF32     // size of a single tile (maximum width & height difference of its corners)
+	viewBounds geom.RectangleF32 // bounds of the view (screen coordinates)
+	viewCenter geom.PointF32     // center of view; calculated
+
+	tileSizeTransformed      geom.PointF32 // calculated
+	tileToViewTransformation geom.PointF32 // calculated
+	viewToTileTransformation geom.PointF32 // calculated
+}
+
+// NewIsometricProjection creates a new isometric projection. By default the tile with the coordinate (0, 0) will be centered in the viewBounds. The tile size is represented with maximum width & height difference of its corners.
+func NewIsometricProjection(tileSize geom.PointF32, viewBounds geom.RectangleF32) *IsometricProjection {
+	p := &IsometricProjection{zoom: 1, tileSize: tileSize, viewBounds: viewBounds}
+	p.update()
+	return p
+}
+
+func (p *IsometricProjection) update() {
+	if p.zoom == 0 {
+		p.zoom = 1
+	}
+	p.zoomInverse = 1 / p.zoom
+
+	p.viewCenter = p.viewBounds.Center()
+
+	p.tileSizeTransformed = p.tileSize.Mul(p.zoom)
+	p.tileToViewTransformation = p.tileSize.Mul(.5 * p.zoom)
+	p.viewToTileTransformation = geom.PtF32(1/p.tileSizeTransformed.X, 1/p.tileSizeTransformed.Y)
+}
+
+// Center gives back the coordinate of the center tile
+func (p *IsometricProjection) Center() geom.PointF32 { return p.center }
+
+// Enumerate enumerates all tiles in the set view bounds and calls action for every tile.
+func (p *IsometricProjection) Enumerate(action func(tile geom.PointF32, view geom.PointF32)) {
+	p.EnumerateInt(func(tile geom.Point, view geom.PointF32) {
+		action(tile.ToF32(), view)
+	})
+}
+
+// EnumerateInt enumerates all tiles in the set view bounds and calls action for every tile.
+func (p *IsometricProjection) EnumerateInt(action func(tile geom.Point, view geom.PointF32)) {
+	visible := p.viewBounds
+	visible.Max.Y += p.tileSize.Y * p.zoom
+	topLeft := p.ViewToTile(geom.PtF32(visible.Min.X, visible.Min.Y))
+	topRight := p.ViewToTile(geom.PtF32(visible.Max.X, visible.Min.Y))
+	bottomLeft := p.ViewToTile(geom.PtF32(visible.Min.X, visible.Max.Y))
+	bottomRight := p.ViewToTile(geom.PtF32(visible.Max.X, visible.Max.Y))
+	minY, maxY := int(geom.Floor32(topRight.Y)), int(geom.Ceil32(bottomLeft.Y))
+	minX, maxX := int(geom.Floor32(topLeft.X)), int(geom.Ceil32(bottomRight.X))
+	tileOffset := p.tileSizeTransformed.Mul(.5)
+	for y := minY; y <= maxY; y++ {
+		for x := minX; x <= maxX; x++ {
+			tile := geom.Pt(x, y)
+			view := p.TileToView(tile.ToF32())
+			if view.X+tileOffset.X < visible.Min.X || view.Y+tileOffset.Y < visible.Min.Y {
+				continue
+			}
+			if view.X-tileOffset.X > visible.Max.X || view.Y-tileOffset.Y > visible.Max.Y {
+				break
+			}
+			action(tile, view)
+		}
+	}
+}
+
+// MoveCenterTo moves the center of the projection to the given tile.
+func (p *IsometricProjection) MoveCenterTo(tile geom.PointF32) {
+	p.center = tile
+	p.update()
+}
+
+// Pan translates the center of the projection with the given delta in view coordinates.
+func (p *IsometricProjection) Pan(delta geom.PointF32) {
+	p.MoveCenterTo(p.center.Add(delta.Mul(p.zoomInverse)))
+}
+
+// SetTileSize sets the size of a single tile (maximum width & height difference of its corners).
+func (p *IsometricProjection) SetTileSize(size geom.PointF32) {
+	p.tileSize = size
+	p.update()
+}
+
+// SetViewBounds sets the bounds of the view coordinates. Used to calculate the center with & for calculating the visible tiles.
+func (p *IsometricProjection) SetViewBounds(bounds geom.RectangleF32) {
+	p.viewBounds = bounds
+	p.update()
+}
+
+// SetZoom changes the zoom to and keeps the around (tile) coordinate on the same position.
+func (p *IsometricProjection) SetZoom(around geom.PointF32, zoom float32) {
+	if p.zoom == zoom {
+		return
+	}
+	p.center = around.Sub(around.Sub(p.center).Mul(p.zoom / zoom))
+	p.zoom = zoom
+	p.update()
+}
+
+// TileInt gives the integer tile coordinate.
+func (p *IsometricProjection) TileInt(tile geom.PointF32) geom.Point {
+	return geom.Pt(int(geom.Round32(tile.X)), int(geom.Round32(tile.Y)))
+}
+
+// TileToView transforms the tile coordinate to the corresponding view coordinate.
+func (p *IsometricProjection) TileToView(tile geom.PointF32) geom.PointF32 {
+	translated := tile.Sub(p.center)
+	return p.viewCenter.Add2D((translated.X-translated.Y)*p.tileToViewTransformation.X, (translated.X+translated.Y)*p.tileToViewTransformation.Y)
+}
+
+// ViewCenter returns the center of the view (calculated from the set view bounds).
+func (p *IsometricProjection) ViewCenter() geom.PointF32 { return p.viewCenter }
+
+// ViewToTile transforms the view coordinate to the corresponding tile coordinate.
+func (p *IsometricProjection) ViewToTile(view geom.PointF32) geom.PointF32 {
+	return p.ViewToTileRelative(view.Sub(p.viewCenter)).Add(p.center)
+}
+
+// ViewToTileInt transforms the view coordinate to the corresponding integer tile coordinate.
+func (p *IsometricProjection) ViewToTileInt(view geom.PointF32) geom.Point {
+	tile := p.ViewToTile(view)
+	return p.TileInt(tile)
+}
+
+// ViewToTileRelative transforms the relative (to 0,0) view coordinate to the corresponding tile coordinate
+func (p *IsometricProjection) ViewToTileRelative(view geom.PointF32) geom.PointF32 {
+	return geom.PtF32(view.X*p.viewToTileTransformation.X+view.Y*p.viewToTileTransformation.Y, -view.X*p.viewToTileTransformation.X+view.Y*p.viewToTileTransformation.Y)
+}
+
+// Zoom returns the current zoom.
+func (p *IsometricProjection) Zoom() float32 { return p.zoom }
+
+// ZoomIn zooms in around the given tile coordinate.
+func (p *IsometricProjection) ZoomIn(around geom.PointF32) {
+	if p.zoom >= 2 {
+		return
+	}
+	p.SetZoom(around, 2*p.zoom)
+}
+
+// ZoomOut zooms in around the given tile coordinate.
+func (p *IsometricProjection) ZoomOut(around geom.PointF32) {
+	if p.zoom <= .25 {
+		return
+	}
+	p.SetZoom(around, .5*p.zoom)
+}

play/isometricprojection_test.go

@@ -0,0 +1,36 @@
+package play
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"opslag.de/schobers/geom"
+)
+
+func createIsometricProjection() *IsometricProjection {
+	return NewIsometricProjection(geom.PtF32(23, 11), geom.RectRelF32(0, 0, 160, 160))
+}
+
+func TestViewToTile(t *testing.T) {
+	p := createIsometricProjection()
+	assert.Equal(t, geom.PtF32(0, 0), p.ViewToTile(geom.PtF32(80, 80)))
+	assert.Equal(t, geom.PtF32(-1, 1), p.ViewToTile(geom.PtF32(57, 80)))
+	assert.Equal(t, geom.PtF32(2, 2), p.ViewToTile(geom.PtF32(80, 102)))
+	assert.Equal(t, geom.PtF32(-1, -3), p.ViewToTile(geom.PtF32(103, 58)))
+}
+
+func TestViewToTileInt(t *testing.T) {
+	p := createIsometricProjection()
+	assert.Equal(t, geom.Pt(0, 0), p.ViewToTileInt(geom.PtF32(80, 80)))
+	assert.Equal(t, geom.Pt(0, 0), p.ViewToTileInt(geom.PtF32(69, 80)))
+	assert.Equal(t, geom.Pt(-1, 1), p.ViewToTileInt(geom.PtF32(68, 80)))
+}
+
+func TestTileToView(t *testing.T) {
+	p := createIsometricProjection()
+	assert.Equal(t, geom.PtF32(80, 80), p.TileToView(geom.PtF32(0, 0)))
+	assert.Equal(t, geom.PtF32(57, 80), p.TileToView(geom.PtF32(-1, 1)))
+	assert.Equal(t, geom.PtF32(80, 102), p.TileToView(geom.PtF32(2, 2)))
+	assert.Equal(t, geom.PtF32(103, 58), p.TileToView(geom.PtF32(-1, -3)))
+}