Sprites in .obj files are composed of Y null-separated records with a probable type field

cmd/view-set/main.go

@@ -1,8 +1,9 @@
 package main
 
 import (
+	"bytes"
 	"flag"
-//	"image/color"
+	"image/color"
 	"log"
 	"math"
 	"os"
@@ -96,7 +97,7 @@ func (e *env) run() {
 				"new state: numObj=%d object=%d (%s) numFrames=%d sprite=%d zoom=%.2f",
 				state.env.set.Count(),
 				state.objIdx,
-				state.env.set.Palette[state.objIdx],
+				state.env.set.Palette[state.objIdx], // FIXME: palette is a confusing name
 				state.curObject().NumSprites,
 				state.spriteIdx,
 				state.zoom,
@@ -115,22 +116,57 @@ func (s *state) runStep(pWin *pixelgl.Window) *state {
 	return &newState
 }
 
+// WIP. Try to convert the pixeldata into a picture.
+func spriteToPic(sprite *data.Sprite) *pixel.PictureData {
+	pic := pixel.MakePictureData(pixel.R(float64(0), float64(0), float64(sprite.Width), float64(sprite.Height)))
+
+	buf := bytes.NewBuffer(sprite.PixelData)
+
+	// The pixeldata seems to be formed of Y null-terminated records, with
+	// varying numbers of bytes in each row. Probably [type, *data] but ignore
+	// type for now.
+	//
+	// Theory: perhaps the data in each X is centered around the origin?
+	for y := 0; y < int(sprite.Height); y++ {
+		rowData, err := buf.ReadBytes(0)
+		if err != nil {
+			log.Printf("Error at y=%d: %v", y, err)
+			continue
+		}
+
+		leftPad := (int(sprite.Width) - len(rowData)) / 2
+
+		for x, b := range rowData {
+			idx := pic.Index(pixel.V(float64(leftPad+x), float64(y)))
+			pic.Pix[idx] = color.RGBA{
+				R: b,
+				G: b,
+				B: b,
+				A: 255,
+			}
+		}
+	}
+
+	return pic
+}
+
 func (s *state) present(pWin *pixelgl.Window) {
-//	obj := s.curObject()
-//	sprite := obj.Sprites[s.spriteIdx]
+	obj := s.curObject()
+	sprite := obj.Sprites[s.spriteIdx]
+	pic := spriteToPic(sprite)
 
 	center := pWin.Bounds().Center()
 
 	cam := pixel.IM
-//	cam = cam.ScaledXY(pixel.ZV, pixel.Vec{1.0, -1.0})  // invert the Y axis
-	cam = cam.Scaled(center, s.zoom)              // apply current zoom factor
+	cam = cam.ScaledXY(center, pixel.Vec{1.0, -1.0}) // invert the Y axis
+	cam = cam.Scaled(center, s.zoom)                 // apply current zoom factor
 	//cam = cam.Moved(center.Sub(s.camPos))           // Make it central
 	//cam = cam.Rotated(center, -0.785) // Apply isometric angle
 	s.cam = cam
 	pWin.SetMatrix(s.cam)
 
-	pWin.Clear(colornames.White)
-//	pixel.NewSprite(pic, pic.Bounds()).Draw(pWin, pixel.IM.Moved(center))
+	pWin.Clear(colornames.Black)
+	pixel.NewSprite(pic, pic.Bounds()).Draw(pWin, pixel.IM.Moved(center))
 }
 
 func (s *state) handleKeys(pWin *pixelgl.Window) {