Improved performance rendering textured floor

- using image.WritePixels instead of NewImageFromImage during Draw

Author: harbdog

camera.go

@@ -223,7 +223,7 @@ func (c *Camera) SetLightRGB(min, max color.NRGBA) {
 // Update - updates the camera view
 func (c *Camera) Update(sprites []Sprite) {
 	// clear horizontal buffer by making a new one
-	c.floorLvl.clear(c.w, c.h)
+	c.floorLvl.initialize(c.w, c.h)
 
 	// reset convergence point
 	c.convergenceDistance = -1
@@ -761,7 +761,7 @@ func (c *Camera) createLevels(numLevels int) []*level {
 // creates floor slices for raycasting floor
 func (c *Camera) createFloorLevel() *horLevel {
 	horizontalLevel := new(horLevel)
-	horizontalLevel.clear(c.w, c.h)
+	horizontalLevel.initialize(c.w, c.h)
 	return horizontalLevel
 }
 

level.go

@@ -38,8 +38,13 @@ func sliceView(width, height int) []*image.Rectangle {
 type horLevel struct {
 	// horBuffer is the image representing the pixels to render during the update
 	horBuffer *image.RGBA
+	// image is the ebitengine image object rendering the horBuffer during draw
+	image *ebiten.Image
 }
 
-func (h *horLevel) clear(width, height int) {
+func (h *horLevel) initialize(width, height int) {
 	h.horBuffer = image.NewRGBA(image.Rect(0, 0, width, height))
+	if h.image == nil {
+		h.image = ebiten.NewImage(width, height)
+	}
 }

render.go

@@ -3,7 +3,6 @@ package raycaster
 import (
 	"image"
 	"image/color"
-	"log"
 
 	"github.com/hajimehoshi/ebiten/v2"
 )
@@ -31,13 +30,12 @@ func (c *Camera) Draw(screen *ebiten.Image) {
 	}
 
 	// draw textured floor
-	floorImg := ebiten.NewImageFromImage(c.floorLvl.horBuffer)
-	if floorImg == nil {
-		log.Fatal("floorImg is nil")
-	} else {
+	if c.floorLvl != nil && c.floorLvl.image != nil {
+		c.floorLvl.image.WritePixels(c.floorLvl.horBuffer.Pix)
+
 		op := &ebiten.DrawImageOptions{}
 		op.Filter = ebiten.FilterNearest
-		screen.DrawImage(floorImg, op)
+		screen.DrawImage(c.floorLvl.image, op)
 	}
 
 	// draw sprites