From aea3c71cf913b7be9d7bdb4ff9d63ac6c8c63d14 Mon Sep 17 00:00:00 2001
From: sumi <sumi@local>
Date: Mon, 22 Dec 2025 17:50:36 -0600
Subject: [PATCH] automated snapshot

---
 contour_layer.go |  2 +-
 main.go          | 26 ++++++++++++++------------
 sketch.go        | 48 ++++++++++++++++++++++++++++++++++++++----------
 3 files changed, 53 insertions(+), 23 deletions(-)

diff --git a/contour_layer.go b/contour_layer.go
index fbf8c73..1c6ca83 100644
--- a/contour_layer.go
+++ b/contour_layer.go
@@ -36,7 +36,7 @@ func (s *ContourLayer) AddActors(n, sourceWidth, sourceHeight int32) {
 				position: rl.Vector2{X: float32(x), Y: float32(y)},
 				field:    s.field,
 				stepSize: 1,
-				color:    rl.NewColor(11, 35, 176, 20),
+				color:    rl.NewColor(11, 35, 176, 50),
 			}
 		s.actors = append(s.actors, newActor)
 	}
diff --git a/main.go b/main.go
index 183ff39..e415bc2 100644
--- a/main.go
+++ b/main.go
@@ -12,16 +12,16 @@ import (
 )
 
 const (
-	targetWidth  = 1000
-	targetHeight = 1000
-	sourceScale  = 2
 	snapshotsDir = "snapshots"
 )
 
 func main() {
 
-	sourceWidth := int32(sourceScale * targetWidth)
-	sourceHeight := int32(sourceScale * targetHeight)
+	var sourceWidth int32 = 8000
+	var sourceHeight int32 = 6400
+
+	var targetWidth int32 = int32(2000)
+	var targetHeight int32 = int32(1200)
 
 	os.MkdirAll(snapshotsDir, 0755)
 	log := log.New(os.Stdout, "", log.Ldate|log.Ltime|log.Lshortfile)
@@ -47,7 +47,7 @@ func main() {
 			x: -float32(sourceWidth / 2.0),
 			y: -float32(sourceHeight / 2.0),
 			field: &ScaleField{
-				scale: 1.0,
+				scale: 4.0,
 				field: &imageField,
 			},
 		}
@@ -74,10 +74,16 @@ func main() {
 		// begin drawing
 		t := time.Since(t0).Seconds()
 
+		targetBounds := rl.Rectangle {
+			X: float32(targetWidth) / 4.0,
+			Y: 0,
+			Width: float32(targetWidth) * 3.0 / 4.0,
+			Height: float32(targetHeight),
+		}
+
 		// set up RenderCtx
 		renderCtx := &RenderCtx{
-			TargetWidth:  int32(targetWidth),
-			TargetHeight: int32(targetHeight),
+			TargetBounds: targetBounds,
 			SourceWidth:  int32(sourceWidth),
 			SourceHeight: int32(sourceHeight),
 			Time:         t,
@@ -91,11 +97,7 @@ func main() {
 		 */
 		rl.BeginDrawing()
 		rl.ClearBackground(rl.Blank)
-
 		sketch.Draw(renderCtx)
-
-		rl.DrawText("Mouse right button drag to move, mouse wheel to zoom", 10, 10, 20, rl.White)
-
 		rl.EndDrawing()
 
 		if rl.IsKeyDown(rl.KeySpace) {
diff --git a/sketch.go b/sketch.go
index 845b476..ba8a296 100644
--- a/sketch.go
+++ b/sketch.go
@@ -54,8 +54,8 @@ func (s *Sketch) Draw(ctx *RenderCtx) {
 	// render onto all layer textures
 	for _, instance := range s.layerToolsOrdered {
 		instance.layer.Update(ctx)
+		layer := instance.layer
 		if instance.layer.IsDirty() {
-			layer := instance.layer
 			rl.BeginTextureMode(*instance.texture)
 			layer.Draw(ctx)
 			rl.EndTextureMode()
@@ -64,12 +64,7 @@ func (s *Sketch) Draw(ctx *RenderCtx) {
 
 	// composite all layers to screen
 
-	screen := rl.Rectangle {
-		X:      0,
-		Y:      0,
-		Width:  float32(ctx.TargetWidth),
-		Height: float32(ctx.TargetHeight),
-	}
+	outputRect := s.calcOutputRectKeepingAspectRatio(ctx)
 
 	// copy from full texture for compositing, with vertical flipping
 	src := rl.Rectangle {
@@ -92,7 +87,40 @@ func (s *Sketch) Draw(ctx *RenderCtx) {
 	}
 	rl.EndTextureMode()
 
-	rl.DrawTexturePro(s.composite.Texture, viewport, screen, rl.Vector2{}, 0, rl.White)
+	rl.DrawTexturePro(s.composite.Texture, viewport, outputRect, rl.Vector2{}, 0, rl.White)
+
+	outlineRect := outputRect.ToInt32()
+	rl.DrawRectangleLines(outlineRect.X, outlineRect.Y, outlineRect.Width, outlineRect.Height, rl.Gray)
+}
+
+func (s *Sketch) calcOutputRectKeepingAspectRatio(ctx *RenderCtx) rl.Rectangle {
+	sourceAspect := float32(ctx.SourceWidth) / float32(ctx.SourceHeight)
+	targetAspect := ctx.TargetBounds.Width / ctx.TargetBounds.Height
+
+	outputWidth := ctx.TargetBounds.Width
+	outputHeight := ctx.TargetBounds.Height
+	
+	if sourceAspect < targetAspect {
+		// source is relatively taller than the target
+		// so we set the output height to the target height
+		// and calculate the width based on source aspect and center
+		outputWidth = outputHeight * sourceAspect
+	} else {
+		// source is relatively wider than the target
+		// so we set the output width to the target width
+		// and calculate the height based on source aspect and center
+		outputHeight = outputWidth / sourceAspect
+	}
+
+	// output width and height are correct -- center within TargetBounds
+	x := ctx.TargetBounds.X + ctx.TargetBounds.Width / 2.0 - outputWidth / 2.0 
+	y := ctx.TargetBounds.Y + ctx.TargetBounds.Height / 2.0 - outputHeight / 2.0 
+
+	return rl.Rectangle {
+		X: x, Y: y,
+		Width: outputWidth,
+		Height: outputHeight,
+	}
 }
 
 func (s *Sketch) CalcViewport(ctx *RenderCtx) rl.Rectangle {
@@ -111,6 +139,7 @@ func (s *Sketch) Update(ctx *RenderCtx) {
 	if rl.IsMouseButtonDown(rl.MouseRightButton) {
 		// get mouse delta from last frame
 		delta := rl.GetMouseDelta()
+		sourceScale := float32(ctx.SourceWidth) / ctx.TargetBounds.Width
 		// compute the amount to move scaled by the camera zoom
 		delta = rl.Vector2Scale(delta, -sourceScale/s.cam.Zoom)
 		delta.Y = -delta.Y
@@ -233,8 +262,7 @@ func (p Ports) Eval(t float64) map[string]float64 {
 /** RenderCtx **/
 
 type RenderCtx struct {
-	TargetWidth  int32
-	TargetHeight int32
+	TargetBounds rl.Rectangle
 	SourceWidth  int32
 	SourceHeight int32
 	Time         float64