Merge pull request #3567 from SuperFromND/gamewidth-fix

fix: Use float versions of gameWidth/gameHeight for w/hScale & render origin

Author: K4thos

src/stage.go

@@ -703,7 +703,7 @@ func (bg backGround) draw(pos [2]float32, drawscl, bgscl, stglscl float32,
 		// Choose render origin: top-left for screenpack/storyboard videos, center for everything else
 		var rcx float32
 		if bg._type != BG_Video || isStage {
-			rcx = float32(sys.gameWidth) / 2
+			rcx = sys.gameWidthFloat / 2
 		}
 
 		bg.anim.Draw(&rect, x-xsoffset, y, sclx, scly,

src/system.go

@@ -65,6 +65,8 @@ type SystemStateVars struct {
 
 	scrrect                 [4]int32
 	gameWidth, gameHeight   int32
+	gameWidthFloat          float32 // Float forms used for precise screenpack math
+	gameHeightFloat         float32 // TODO: rework gameWidth/gameHeight as floats instead
 	widthScale, heightScale float32
 	gameEnd, frameSkip      bool
 	paused, frameStepFlag   bool
@@ -617,17 +619,21 @@ func (s *System) setGameSize(w, h int32) {
 
 	if screenAspect > targetAspect {
 		// Screen is wider than 4:3 - scale based on height
-		s.gameWidth = int32(float32(baseHeight) * screenAspect)
+		s.gameWidthFloat = float32(baseHeight) * screenAspect
+		s.gameWidth = int32(s.gameWidthFloat)
 		s.gameHeight = baseHeight
+		s.gameHeightFloat = float32(s.gameHeight)
 	} else {
 		// Screen is taller than 4:3 - scale based on width
 		s.gameWidth = baseWidth
-		s.gameHeight = int32(float32(baseWidth) / screenAspect)
+		s.gameWidthFloat = float32(baseWidth)
+		s.gameHeightFloat = float32(baseWidth) / screenAspect
+		s.gameHeight = int32(s.gameHeightFloat)
 	}
 
 	// Update scale
-	s.widthScale = float32(s.scrrect[2]) / float32(s.gameWidth)
-	s.heightScale = float32(s.scrrect[3]) / float32(s.gameHeight)
+	s.widthScale = float32(s.scrrect[2]) / s.gameWidthFloat
+	s.heightScale = float32(s.scrrect[3]) / s.gameHeightFloat
 }
 
 // Change aspect ratio at match start