Add zfast-lcd shader (#431)

menu/scene_settings.go

@@ -182,7 +182,7 @@ var incrCallbacks = map[string]callbackIncrement{
 		settings.Save()
 	},
 	"VideoFilter": func(f *structs.Field, direction int) {
-		filters := []string{"Raw", "Smooth", "Pixel Perfect", "CRT"}
+		filters := []string{"Raw", "Smooth", "Pixel Perfect", "CRT", "LCD"}
 		v := f.Value().(string)
 		i := utils.IndexOfString(v, filters)
 		i += direction

video/lcd_frag_shader.go

@@ -0,0 +1,48 @@
+package video
+
+var zfastLCDFragmentShader = `
+#if __VERSION__ >= 130
+#define COMPAT_VARYING in
+#define COMPAT_ATTRIBUTE in
+#define COMPAT_TEXTURE texture
+#define COMPAT_FRAGCOLOR FragColor
+out vec4 COMPAT_FRAGCOLOR;
+#else
+#define COMPAT_VARYING varying
+#define COMPAT_ATTRIBUTE attribute
+#define COMPAT_TEXTURE texture2D
+#define COMPAT_FRAGCOLOR gl_FragColor
+#endif
+
+uniform vec2 OutputSize;
+uniform vec2 TextureSize;
+uniform vec2 InputSize;
+uniform sampler2D Texture;
+COMPAT_VARYING vec2 fragTexCoord;
+
+#define BORDERMULT 14.0
+#define GBAGAMMA 1.0
+
+void main() {
+  vec2 texcoordInPixels = fragTexCoord.xy * TextureSize.xy;
+  vec2 centerCoord = floor(texcoordInPixels.xy)+vec2(0.5,0.5);
+  vec2 distFromCenter = abs(centerCoord - texcoordInPixels);
+  vec2 invSize = 1.0/TextureSize.xy;
+
+  float Y = max(distFromCenter.x,(distFromCenter.y));
+
+  Y=Y*Y;
+  float YY = Y*Y;
+  float YYY = YY*Y;
+
+  float LineWeight = YY - 2.7*YYY;
+  LineWeight = 1.0 - BORDERMULT*LineWeight;
+
+  vec3 colour = COMPAT_TEXTURE(Texture, invSize*centerCoord).rgb*LineWeight;
+
+  if (GBAGAMMA > 0.5)
+    colour.rgb*=0.6+0.4*(colour.rgb); //fake gamma because the pi is too slow!
+    
+  COMPAT_FRAGCOLOR = vec4(colour.rgb , 1.0);
+}
+` + "\x00"

video/video.go

@@ -25,6 +25,7 @@ type Video struct {
 	defaultProgram       uint32 // default program used for the game quad
 	sharpBilinearProgram uint32 // sharp bilinear program used for the game quad
 	zfastCRTProgram      uint32 // fast CRT program used for the game quad
+	zfastLCDProgram      uint32 // fast LCD program used for the game quad
 	roundedProgram       uint32 // program to draw rectangles with rounded corners
 	borderProgram        uint32 // program to draw rectangles borders
 	circleProgram        uint32 // program to draw textured circles
@@ -139,6 +140,11 @@ func (video *Video) Configure(fullscreen bool) {
 		panic(err)
 	}
 
+	video.zfastLCDProgram, err = newProgram(vertexShader, zfastLCDFragmentShader)
+	if err != nil {
+		panic(err)
+	}
+
 	video.roundedProgram, err = newProgram(vertexShader, roundedFragmentShader)
 	if err != nil {
 		panic(err)
@@ -211,6 +217,7 @@ func (video *Video) Configure(fullscreen bool) {
 // Smooth: linear
 // Pixel Perfect: sharp-bilinear
 // CRT: zfast-crt
+// LCD: zfast-lcd
 func (video *Video) UpdateFilter(filter string) {
 	gl.BindTexture(gl.TEXTURE_2D, video.texID)
 	switch filter {
@@ -226,6 +233,10 @@ func (video *Video) UpdateFilter(filter string) {
 		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
 		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
 		video.program = video.zfastCRTProgram
+	case "LCD":
+		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
+		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
+		video.program = video.zfastLCDProgram
 	case "Raw":
 		fallthrough
 	default: