From 93c09633eec965fce3cf279021a95594b80e45e8 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Fri, 14 Oct 2022 16:04:04 +0900
Subject: [PATCH] examples/shader: bug fix: wrong function usages

The tex-coord should have been modified by the source texture
region/size, rather than the destination texture's.
---
 examples/shader/crt.go | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/examples/shader/crt.go b/examples/shader/crt.go
index 72ce64fce..262ec0ddc 100644
--- a/examples/shader/crt.go
+++ b/examples/shader/crt.go
@@ -23,37 +23,37 @@ var ScreenSize vec2
 
 func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 	const (
-		BLURSCALEX  = 0.45
-		LOWLUMSCAN  = 5.0
-		HILUMSCAN   = 10.0
-		BRIGHTBOOST = 1.25
-		MASK_DARK   = 0.25
-		MASK_FADE   = 0.8
+		blurScaleX  = 0.45
+		lowLumScan  = 5.0
+		hiLumScan   = 10.0
+		BrightBoost = 1.25
+		maskDark    = 0.25
+		maskFade    = 0.8
 	)
 
 	pos := texCoord
-	origin, size := imageDstRegionOnTexture()
+	origin, size := imageSrcRegionOnTexture()
 	pos -= origin
 	pos /= size
 
-	maskFade := 0.3333 * MASK_FADE
-	invDims := 1.0 / imageDstTextureSize().xy
-	p := pos * imageDstTextureSize()
+	maskFade := 0.3333 * maskFade
+	invDims := 1.0 / imageSrcTextureSize().xy
+	p := pos * imageSrcTextureSize()
 	i := floor(p) + 0.50
 	f := p - i
 	p = (i + 4.0*f*f*f) * invDims
-	p.x = mix(p.x, pos.x, BLURSCALEX)
+	p.x = mix(p.x, pos.x, blurScaleX)
 	Y := f.y * f.y
 	YY := Y * Y
 	whichmask := fract(pos.x * -0.4999)
 	mask := 1.0
 	if whichmask < 0.5 {
-		mask -= MASK_DARK
+		mask -= maskDark
 	}
 
 	clr := imageSrc2At(p*size + origin).rgb
-	scanLineWeight := (BRIGHTBOOST - LOWLUMSCAN*(Y-2.05*YY))
-	scanLineWeightB := 1.0 - HILUMSCAN*(YY-2.8*YY*Y)
+	scanLineWeight := (BrightBoost - lowLumScan*(Y-2.05*YY))
+	scanLineWeightB := 1.0 - hiLumScan*(YY-2.8*YY*Y)
 
 	return vec4(clr.rgb*mix(scanLineWeight*mask, scanLineWeightB, dot(clr.rgb, vec3(maskFade))), 1.0)
 }