From 289a0e9f281c98c454ceeb2f7612ed9e81fdad1c Mon Sep 17 00:00:00 2001
From: Shane Duncan <shane.duncan56@gmail.com>
Date: Thu, 31 Jul 2025 15:24:13 +1000
Subject: [PATCH 1/4] add isometric renderer

---
 assets/test_isometric.tmx           |  76 ++++++++++++++++++++++++++++
 assets/tilesets/isometric.tsx       |   4 ++
 assets/tilesets/isometric_tiles.png | Bin 0 -> 2251 bytes
 render/isometric.go                 |  54 ++++++++++++++++++++
 render/renderer.go                  |   8 ++-
 render/renderer_test.go             |  57 +++++++++++++++++++++
 6 files changed, 197 insertions(+), 2 deletions(-)
 create mode 100644 assets/test_isometric.tmx
 create mode 100755 assets/tilesets/isometric.tsx
 create mode 100755 assets/tilesets/isometric_tiles.png
 create mode 100644 render/isometric.go
 create mode 100644 render/renderer_test.go

diff --git a/assets/test_isometric.tmx b/assets/test_isometric.tmx
new file mode 100644
index 0000000..aa82c44
--- /dev/null
+++ b/assets/test_isometric.tmx
@@ -0,0 +1,76 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<map version="1.10" tiledversion="1.11.2" orientation="isometric" renderorder="right-down" width="30" height="20" tilewidth="32" tileheight="16" infinite="0" nextlayerid="4" nextobjectid="1">
+ <tileset firstgid="1" source="tilesets/isometric.tsx"/>
+ <layer id="1" name="Tile Layer 1" width="30" height="20">
+  <data encoding="csv">
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,9,9,9,9,9,9,9,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,9,9,9,9,9,9,9,9,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,9,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,12,12,12,12,12,12,12,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
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+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,2,2,2,2
+</data>
+ </layer>
+ <layer id="2" name="Tile Layer 2" width="30" height="20">
+  <data encoding="csv">
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+</data>
+ </layer>
+ <layer id="3" name="Tile Layer 3" width="30" height="20">
+  <data encoding="csv">
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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+</data>
+ </layer>
+</map>
diff --git a/assets/tilesets/isometric.tsx b/assets/tilesets/isometric.tsx
new file mode 100755
index 0000000..19ab86a
--- /dev/null
+++ b/assets/tilesets/isometric.tsx
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<tileset version="1.10" tiledversion="1.11.2" name="isotiles" tilewidth="32" tileheight="32" tilecount="64" columns="8">
+ <image source="isometric_tiles.png" width="256" height="256"/>
+</tileset>
diff --git a/assets/tilesets/isometric_tiles.png b/assets/tilesets/isometric_tiles.png
new file mode 100755
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diff --git a/render/isometric.go b/render/isometric.go
new file mode 100644
index 0000000..2d71594
--- /dev/null
+++ b/render/isometric.go
@@ -0,0 +1,54 @@
+package render
+
+import (
+	"image"
+
+	"github.com/disintegration/imaging"
+	"github.com/lafriks/go-tiled"
+)
+
+type IsometricRendererEngine struct {
+	m *tiled.Map
+}
+
+func (e *IsometricRendererEngine) Init(m *tiled.Map) {
+	e.m = m
+}
+
+func (e *IsometricRendererEngine) GetFinalImageSize() image.Rectangle {
+	return image.Rect(0, 0, e.m.Width*e.m.TileWidth, e.m.Height*e.m.TileHeight)
+}
+
+func (e *IsometricRendererEngine) RotateTileImage(tile *tiled.LayerTile, img image.Image) image.Image {
+	timg := img
+	if tile.DiagonalFlip {
+		timg = imaging.FlipH(imaging.Rotate270(timg))
+	}
+	if tile.HorizontalFlip {
+		timg = imaging.FlipH(timg)
+	}
+	if tile.VerticalFlip {
+		timg = imaging.FlipV(timg)
+	}
+
+	return timg
+}
+
+func (e *IsometricRendererEngine) GetTilePosition(x, y int) image.Rectangle {
+    tw, th := e.m.TileWidth, e.m.TileHeight
+
+	ratio := tw / th
+
+	stepX := tw / ratio
+	stepY := th / ratio
+
+	actualSpriteHeight := th * ratio
+
+    offsetX := e.m.Width * stepX
+	offsetY := -th
+
+    sx := (x - y) * stepX + offsetX - (tw / ratio)
+    sy := (x + y) * stepY + offsetY
+
+    return image.Rect(sx, sy, sx + tw, sy + actualSpriteHeight)
+}
\ No newline at end of file
diff --git a/render/renderer.go b/render/renderer.go
index 56d4c48..cdb2ae5 100644
--- a/render/renderer.go
+++ b/render/renderer.go
@@ -74,10 +74,14 @@ func NewRenderer(m *tiled.Map) (*Renderer, error) {
 // NewRendererWithFileSystem creates new rendering engine instance with a custom file system.
 func NewRendererWithFileSystem(m *tiled.Map, fs fs.FS) (*Renderer, error) {
 	r := &Renderer{m: m, tileCache: make(map[uint32]image.Image), fs: fs}
-	if r.m.Orientation == "orthogonal" {
+	switch r.m.Orientation {
+	case "orthogonal":
 		r.engine = &OrthogonalRendererEngine{}
-	} else {
+	case "isometric":
+		r.engine = &IsometricRendererEngine{}
+	default:
 		return nil, ErrUnsupportedOrientation
+
 	}
 
 	r.engine.Init(r.m)
diff --git a/render/renderer_test.go b/render/renderer_test.go
new file mode 100644
index 0000000..778e92a
--- /dev/null
+++ b/render/renderer_test.go
@@ -0,0 +1,57 @@
+package render
+
+import (
+	"os"
+	"testing"
+
+	"github.com/lafriks/go-tiled"
+)
+
+func TestRenderer_RenderOrthogonalMap(t *testing.T) {
+	tiledMap, err := tiled.LoadFile("../assets/test_wangsets_map.tmx")
+
+		if err != nil {
+		t.Error(err)
+		return
+	}
+
+	renderer, err := NewRenderer(tiledMap)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	renderer.RenderVisibleLayers()
+
+	w, _ := os.Create("../assets/test_orthogonal.png")
+	defer w.Close()
+
+	if err = renderer.SaveAsPng(w); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestRenderer_RenderIsometricMap(t *testing.T) {
+	tiledMap, err := tiled.LoadFile("../assets/test_isometric.tmx")
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	renderer, err := NewRenderer(tiledMap)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	renderer.RenderVisibleLayers()
+	//renderer.RenderLayer(0)
+
+	w, _ := os.Create("../assets/test_render_isomap.png")
+	defer w.Close()
+
+	if err = renderer.SaveAsPng(w); err != nil {
+		t.Error(err)
+	}
+
+}
\ No newline at end of file

From c0a540dc4e754d24b5049b90671df77ce6205d70 Mon Sep 17 00:00:00 2001
From: Shane Duncan <shane.duncan56@gmail.com>
Date: Wed, 6 Aug 2025 12:01:18 +1000
Subject: [PATCH 2/4] correct isometric output working

---
 render/isometric.go     | 11 +++++++----
 render/renderer_test.go | 18 ++++++++++++++++--
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/render/isometric.go b/render/isometric.go
index 2d71594..e08b29d 100644
--- a/render/isometric.go
+++ b/render/isometric.go
@@ -16,7 +16,11 @@ func (e *IsometricRendererEngine) Init(m *tiled.Map) {
 }
 
 func (e *IsometricRendererEngine) GetFinalImageSize() image.Rectangle {
-	return image.Rect(0, 0, e.m.Width*e.m.TileWidth, e.m.Height*e.m.TileHeight)
+	side := e.m.Height + e.m.Width
+	hx := side * e.m.TileWidth/2
+	hy := side * e.m.TileHeight/2
+
+	return image.Rect(0, 0, hx, hy)
 }
 
 func (e *IsometricRendererEngine) RotateTileImage(tile *tiled.LayerTile, img image.Image) image.Image {
@@ -44,11 +48,10 @@ func (e *IsometricRendererEngine) GetTilePosition(x, y int) image.Rectangle {
 
 	actualSpriteHeight := th * ratio
 
-    offsetX := e.m.Width * stepX
-	offsetY := -th
+    offsetX := e.m.Height * e.m.TileWidth/2
 
     sx := (x - y) * stepX + offsetX - (tw / ratio)
-    sy := (x + y) * stepY + offsetY
+    sy := (x + y) * stepY - (th)
 
     return image.Rect(sx, sy, sx + tw, sy + actualSpriteHeight)
 }
\ No newline at end of file
diff --git a/render/renderer_test.go b/render/renderer_test.go
index 778e92a..24ec35b 100644
--- a/render/renderer_test.go
+++ b/render/renderer_test.go
@@ -1,10 +1,13 @@
 package render
 
 import (
+	"image"
 	"os"
 	"testing"
 
 	"github.com/lafriks/go-tiled"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestRenderer_RenderOrthogonalMap(t *testing.T) {
@@ -45,13 +48,24 @@ func TestRenderer_RenderIsometricMap(t *testing.T) {
 	}
 
 	renderer.RenderVisibleLayers()
-	//renderer.RenderLayer(0)
+	//renderer.RenderLayer(0)'
 
-	w, _ := os.Create("../assets/test_render_isomap.png")
+	outputPath := "../assets/test_render_isomap.png"
+
+	w, _ := os.Create(outputPath)
 	defer w.Close()
 
 	if err = renderer.SaveAsPng(w); err != nil {
 		t.Error(err)
 	}
 
+	file, err := os.Open(outputPath)
+	require.NoError(t, err)
+	defer file.Close()
+
+	img, _, err := image.Decode(file)
+	require.NoError(t, err)
+
+	assert.Equal(t, 800, img.Bounds().Dx(), "image width should be 800 pixels")
+	assert.Equal(t, 400, img.Bounds().Dy(), "image height should be 400 pixels")
 }
\ No newline at end of file

From 2dc663f57bfcb86385bf03d9fe7616633a3dc40a Mon Sep 17 00:00:00 2001
From: Shane Duncan <shane.duncan56@gmail.com>
Date: Tue, 9 Sep 2025 11:22:28 +1000
Subject: [PATCH 3/4] use tile image widths for rendering rather than map
 position widths

---
 render/isometric.go  | 21 ++++++++++++---------
 render/orthogonal.go |  8 +++-----
 render/renderer.go   |  7 ++++---
 3 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/render/isometric.go b/render/isometric.go
index e08b29d..05bb277 100644
--- a/render/isometric.go
+++ b/render/isometric.go
@@ -38,20 +38,23 @@ func (e *IsometricRendererEngine) RotateTileImage(tile *tiled.LayerTile, img ima
 	return timg
 }
 
-func (e *IsometricRendererEngine) GetTilePosition(x, y int) image.Rectangle {
+func (e *IsometricRendererEngine) GetTilePosition(x, y int) image.Point {
     tw, th := e.m.TileWidth, e.m.TileHeight
 
-	ratio := tw / th
+	stepX := tw / 2
+	stepY := th / 2
 
-	stepX := tw / ratio
-	stepY := th / ratio
-
-	actualSpriteHeight := th * ratio
+	//actualSpriteHeight := th * 2
 
     offsetX := e.m.Height * e.m.TileWidth/2
 
-    sx := (x - y) * stepX + offsetX - (tw / ratio)
-    sy := (x + y) * stepY - (th)
+	offsetY := 0
+	if tw > th {
+		offsetY = -th
+	}
+
+    sx := (x - y) * stepX + offsetX - stepX
+    sy := (x + y) * stepY + offsetY
 
-    return image.Rect(sx, sy, sx + tw, sy + actualSpriteHeight)
+    return image.Pt(sx, sy)
 }
\ No newline at end of file
diff --git a/render/orthogonal.go b/render/orthogonal.go
index cfe762d..0f2de33 100644
--- a/render/orthogonal.go
+++ b/render/orthogonal.go
@@ -61,9 +61,7 @@ func (e *OrthogonalRendererEngine) RotateTileImage(tile *tiled.LayerTile, img im
 }
 
 // GetTilePosition returns tile position in image.
-func (e *OrthogonalRendererEngine) GetTilePosition(x, y int) image.Rectangle {
-	return image.Rect(x*e.m.TileWidth,
-		y*e.m.TileHeight,
-		(x+1)*e.m.TileWidth,
-		(y+1)*e.m.TileHeight)
+func (e *OrthogonalRendererEngine) GetTilePosition(x, y int) image.Point {
+	return image.Pt(x*e.m.TileWidth,
+		y*e.m.TileHeight)
 }
diff --git a/render/renderer.go b/render/renderer.go
index cdb2ae5..e0eebff 100644
--- a/render/renderer.go
+++ b/render/renderer.go
@@ -54,7 +54,7 @@ type RendererEngine interface {
 	Init(m *tiled.Map)
 	GetFinalImageSize() image.Rectangle
 	RotateTileImage(tile *tiled.LayerTile, img image.Image) image.Image
-	GetTilePosition(x, y int) image.Rectangle
+	GetTilePosition(x, y int) image.Point
 }
 
 // Renderer represents an rendering engine.
@@ -169,13 +169,14 @@ func (r *Renderer) _renderLayer(layer *tiled.Layer) error {
 			}
 
 			pos := r.engine.GetTilePosition(x, y)
+			renderRect := image.Rect(pos.X, pos.Y, pos.X + img.Bounds().Dx(), pos.Y + img.Bounds().Dy())
 
 			if layer.Opacity < 1 {
 				mask := image.NewUniform(color.Alpha{uint8(layer.Opacity * 255)})
 
-				draw.DrawMask(r.Result, pos, img, img.Bounds().Min, mask, mask.Bounds().Min, draw.Over)
+				draw.DrawMask(r.Result, renderRect, img, img.Bounds().Min, mask, mask.Bounds().Min, draw.Over)
 			} else {
-				draw.Draw(r.Result, pos, img, img.Bounds().Min, draw.Over)
+				draw.Draw(r.Result, renderRect, img, img.Bounds().Min, draw.Over)
 			}
 
 			i++

From 7da1011839d75c89f66ee46f4743a22e2bdd6e10 Mon Sep 17 00:00:00 2001
From: Shane Duncan <shane.duncan56@gmail.com>
Date: Thu, 11 Sep 2025 11:51:14 +1000
Subject: [PATCH 4/4] add test output folder, cleanup

---
 .gitignore                    |  1 +
 assets/test_isometric.tmx     |  4 ++--
 render/isometric.go           |  6 ++----
 render/render_objects_test.go |  2 +-
 render/renderer_test.go       | 18 ++++++++++++++----
 5 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/.gitignore b/.gitignore
index 4502932..f3f73ff 100644
--- a/.gitignore
+++ b/.gitignore
@@ -27,3 +27,4 @@ debug
 /tmx2img
 vendor/
 map.png
+assets/test_output/
diff --git a/assets/test_isometric.tmx b/assets/test_isometric.tmx
index aa82c44..80e2f6c 100644
--- a/assets/test_isometric.tmx
+++ b/assets/test_isometric.tmx
@@ -29,10 +29,10 @@
   <data encoding="csv">
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1073741835,0,2147483659,0,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
-0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
-0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1610612751,0,2684354572,3221225486,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,9,9,11,0,0,0,0,0,0,0,
diff --git a/render/isometric.go b/render/isometric.go
index 05bb277..96153f4 100644
--- a/render/isometric.go
+++ b/render/isometric.go
@@ -44,17 +44,15 @@ func (e *IsometricRendererEngine) GetTilePosition(x, y int) image.Point {
 	stepX := tw / 2
 	stepY := th / 2
 
-	//actualSpriteHeight := th * 2
-
     offsetX := e.m.Height * e.m.TileWidth/2
 
 	offsetY := 0
 	if tw > th {
-		offsetY = -th
+	    offsetY = tw - th
 	}
 
     sx := (x - y) * stepX + offsetX - stepX
-    sy := (x + y) * stepY + offsetY
+    sy := (x + y) * stepY - offsetY
 
     return image.Pt(sx, sy)
 }
\ No newline at end of file
diff --git a/render/render_objects_test.go b/render/render_objects_test.go
index 20820cb..71ad447 100644
--- a/render/render_objects_test.go
+++ b/render/render_objects_test.go
@@ -41,7 +41,7 @@ func TestRenderer_RenderObjectGroup(t *testing.T) {
 
 	renderer.RenderObjectGroup(0)
 
-	w, _ := os.Create("../assets/test_render_objects.png")
+	w, _ := os.Create("../assets/test_output/test_render_objects.png")
 	defer w.Close()
 
 	if err = renderer.SaveAsPng(w); err != nil {
diff --git a/render/renderer_test.go b/render/renderer_test.go
index 24ec35b..7a841b3 100644
--- a/render/renderer_test.go
+++ b/render/renderer_test.go
@@ -4,16 +4,27 @@ import (
 	"image"
 	"os"
 	"testing"
+	"path/filepath"
 
 	"github.com/lafriks/go-tiled"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
+func TestMain(m *testing.M) {
+	dir := filepath.Join("..", "assets", "test_output")
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		os.Exit(1)
+	}
+
+	exitCode := m.Run()
+	os.Exit(exitCode)
+}
+
 func TestRenderer_RenderOrthogonalMap(t *testing.T) {
 	tiledMap, err := tiled.LoadFile("../assets/test_wangsets_map.tmx")
 
-		if err != nil {
+	if err != nil {
 		t.Error(err)
 		return
 	}
@@ -26,7 +37,7 @@ func TestRenderer_RenderOrthogonalMap(t *testing.T) {
 
 	renderer.RenderVisibleLayers()
 
-	w, _ := os.Create("../assets/test_orthogonal.png")
+	w, _ := os.Create("../assets/test_output/test_render_orthogonal.png")
 	defer w.Close()
 
 	if err = renderer.SaveAsPng(w); err != nil {
@@ -48,9 +59,8 @@ func TestRenderer_RenderIsometricMap(t *testing.T) {
 	}
 
 	renderer.RenderVisibleLayers()
-	//renderer.RenderLayer(0)'
 
-	outputPath := "../assets/test_render_isomap.png"
+	outputPath := "../assets/test_output/test_render_isomap.png"
 
 	w, _ := os.Create(outputPath)
 	defer w.Close()