Remove old upscalers, rename parameters

assets/shaders/defaultshaders.ini

@@ -99,28 +99,14 @@ Vertex=upscale_bicubic.vsh
 OutputResolution=True
 RequiresIntSupport=True
 Upscaling=True
-SettingName1=B
+SettingName1=Sharpness
-SettingDefaultValue1=0.0
+SettingDefaultValue1=1.0
 SettingMaxValue1=2.0
-SettingMinValue1=-1.0
+SettingMinValue1=-2.0
-SettingName2=C
+SettingName2=Anisotropy
-SettingDefaultValue2=0.5
+SettingDefaultValue2=0.0
 SettingMaxValue2=2.0
-SettingMinValue2=-1.0
+SettingMinValue2=-2.0
-[CatmullRom]
-Name=Bicubic (Catmull-Rom) Upscaler
-Fragment=upscale_catmull_rom.fsh
-Vertex=upscale_catmull_rom.vsh
-OutputResolution=True
-RequiresIntSupport=True
-Upscaling=True
-[MitchellNetravali]
-Name=Bicubic (Mitchell-Netravali) Upscaler
-Fragment=upscale_mitchell_netravali.fsh
-Vertex=upscale_mitchell_netravali.vsh
-OutputResolution=True
-RequiresIntSupport=True
-Upscaling=True
 [UpscaleSpline36]
 Name=Spline36 Upscaler
 Fragment=upscale_spline36.fsh

assets/shaders/upscale_bicubic.fsh

@@ -1,4 +1,6 @@
 // Bicubic upscaling shader.
+// Implements Mitchell-Netravali class filters (aka BC-splines), see:
+// https://en.wikipedia.org/wiki/Mitchell%E2%80%93Netravali_filters .
 
 #ifdef GL_ES
 precision mediump float;
@@ -12,8 +14,17 @@ uniform vec2 u_texelDelta;
 uniform vec2 u_pixelDelta;
 
 uniform vec4 u_setting;
-// u_setting.x - B
+// Shader parameters (somewhat poorly named):
-// u_setting.y - C
+//   u_setting.x - Sharpness
+//   u_setting.y - Anisotropy
+// from which filter coefficients are computed as
+//   B = 1 - Sharpness + 0.5*Anisotropy
+//   C = 0.5 * Sharpness + Anisotropy
+
+// Note: some popular filters are
+//   B-spline                 - B=1, C=0   <=> Sharpness=0,   Anisotropy=0
+//   'The' Mitchell-Netravali - B=C=1/3    <=> Sharpness=2/3, Anisotropy=0
+//   Catmull-Rom              - B=0, C=1/2 <=> Sharpness=1,   Anisotropy=0
 
 const vec2 HALF_PIXEL = vec2(0.5, 0.5);
 
@@ -25,7 +36,7 @@ vec4 getWeights(mat4 W, float t) {
 	return W * vec4(1.0, t, t*t, t*t*t);
 }
 
-vec3 interpolateHorizontally(ivec2 inputPosFloor, int dy, vec4 w) {
+vec3 filterX(ivec2 inputPosFloor, int dy, vec4 w) {
 	return
 		w.x * rgb(inputPosFloor.x - 1, inputPosFloor.y + dy) +
 		w.y * rgb(inputPosFloor.x    , inputPosFloor.y + dy) +
@@ -33,28 +44,33 @@ vec3 interpolateHorizontally(ivec2 inputPosFloor, int dy, vec4 w) {
 		w.w * rgb(inputPosFloor.x + 2, inputPosFloor.y + dy);
 }
 
-vec4 process(vec2 outputPos, float B, float C) {
+vec4 filterBC(vec2 outputPos, float B, float C) {
 	vec2 inputPos = outputPos / u_texelDelta - HALF_PIXEL;
 	ivec2 inputPosFloor = ivec2(inputPos);
-
 	float x = inputPos.x - float(inputPosFloor.x);
 	float y = inputPos.y - float(inputPosFloor.y);
+	const float r6 = 0.166666666, r3 = 0.333333333; // Precomputed 1/6 and 1/3.
+	// Matrix for computing weights.
+	// NOTE: column-major.
 	mat4 W = mat4(
-		B/6.0      , 1.0-B/3.0   , B/6.0           , 0.0    ,
+		B*r6       , 1.0-B*r3    , B*r6            , 0.0   ,
 		-C-0.5*B   , 0.0         , C+0.5*B         , 0.0   ,
 		2.0*C+0.5*B, C+2.0*B-3.0 , -2.0*C-2.5*B+3.0, -C    ,
-		-C-B/6.0   , -C-1.5*B+2.0, C+1.5*B-2.0     , C+B/6.0);
+		-C-B*r6    , -C-1.5*B+2.0, C+1.5*B-2.0     , C+B*r6);
 	vec4 Wx = getWeights(W, x);
 	vec4 Wy = getWeights(W, y);
 
 	vec3 ret =
-		Wy.x * interpolateHorizontally(inputPosFloor, -1, Wx) +
+		Wy.x * filterX(inputPosFloor, -1, Wx) +
-		Wy.y * interpolateHorizontally(inputPosFloor,  0, Wx) +
+		Wy.y * filterX(inputPosFloor,  0, Wx) +
-		Wy.z * interpolateHorizontally(inputPosFloor, +1, Wx) +
+		Wy.z * filterX(inputPosFloor, +1, Wx) +
-		Wy.w * interpolateHorizontally(inputPosFloor, +2, Wx);
+		Wy.w * filterX(inputPosFloor, +2, Wx);
 	return vec4(ret, 1.0);
 }
 
 void main() {
-	gl_FragColor.rgba = process(v_position, u_setting.x, u_setting.y);
+	gl_FragColor.rgba = filterBC(
+		v_position,
+		dot(u_setting.xy, vec2(-1.0, 0.5)) + 1.0,
+		dot(u_setting.xy, vec2(0.5, +1.0)));
 }

assets/shaders/upscale_catmull_rom.fsh

@@ -1,54 +0,0 @@
-// Bicubic (Catmull-Rom) upscaling shader.
-
-#ifdef GL_ES
-precision mediump float;
-precision mediump int;
-#endif
-
-uniform sampler2D sampler0;
-varying vec2 v_position;
-
-uniform vec2 u_texelDelta;
-uniform vec2 u_pixelDelta;
-
-const vec2 HALF_PIXEL = vec2(0.5, 0.5);
-
-vec3 rgb(int inputX, int inputY)
-{
-	return texture2D(sampler0, (vec2(inputX, inputY) + HALF_PIXEL) * u_texelDelta).xyz;
-}
-
-// Catmull-Rom coefficients, multiplied by 2.
-float A(float x) {return x*((2.0-x)*x-1.0);}
-float B(float x) {return x*x*(3.0*x-5.0)+2.0;}
-float C(float x) {return x*((4.0-3.0*x)*x+1.0);}
-float D(float x) {return x*x*(x-1.0);}
-
-vec3 interpolateHorizontally(vec2 inputPos, ivec2 inputPosFloor, int dy) {
-	vec3 ret = vec3(0.0);
-	float x = inputPos.x - float(inputPosFloor.x);
-
-	ret += A(x) * rgb(inputPosFloor.x - 1, inputPosFloor.y + dy);
-        ret += B(x) * rgb(inputPosFloor.x    , inputPosFloor.y + dy);
-        ret += C(x) * rgb(inputPosFloor.x + 1, inputPosFloor.y + dy);
-        ret += D(x) * rgb(inputPosFloor.x + 2, inputPosFloor.y + dy);
-	return ret;
-}
-
-vec4 process(vec2 outputPos) {
-	vec2 inputPos = outputPos / u_texelDelta - HALF_PIXEL;
-	ivec2 inputPosFloor = ivec2(inputPos);
-
-        vec3 ret = vec3(0.0);
-	float y = inputPos.y - float(inputPosFloor.y);
-	ret += A(y) * interpolateHorizontally(inputPos, inputPosFloor, -1);
-	ret += B(y) * interpolateHorizontally(inputPos, inputPosFloor,  0);
-	ret += C(y) * interpolateHorizontally(inputPos, inputPosFloor, +1);
-	ret += D(y) * interpolateHorizontally(inputPos, inputPosFloor, +2);
-	return vec4(0.25 * ret, 1.0);
-}
-
-void main()
-{
-        gl_FragColor.rgba = process(v_position);
-}

assets/shaders/upscale_catmull_rom.vsh

@@ -1,11 +0,0 @@
-attribute vec4 a_position;
-attribute vec2 a_texcoord0;
-
-varying vec2 v_position;
-
-void main()
-{
-  gl_Position = a_position;
-      
-  v_position = a_texcoord0;
-}

assets/shaders/upscale_mitchell_netravali.fsh

@@ -1,54 +0,0 @@
-// Bicubic (Mitchell–Netravali, B=1/3, C=1/3) upscaling shader.
-
-#ifdef GL_ES
-precision mediump float;
-precision mediump int;
-#endif
-
-uniform sampler2D sampler0;
-varying vec2 v_position;
-
-uniform vec2 u_texelDelta;
-uniform vec2 u_pixelDelta;
-
-const vec2 HALF_PIXEL = vec2(0.5, 0.5);
-
-vec3 rgb(int inputX, int inputY)
-{
-	return texture2D(sampler0, (vec2(inputX, inputY) + HALF_PIXEL) * u_texelDelta).xyz;
-}
-
-// Mitchell–Netravali coefficients, multiplied by 18.
-float A(float x) {return ((-7.0*x+15.0)*x-9.0)*x+1.0;}
-float B(float x) {return (21.0*x-36.0)*x*x+16.0;}
-float C(float x) {return ((-21.0*x+27.0)*x+9.0)*x+1.0;}
-float D(float x) {return (7.0*x-6.0)*x*x;}
-
-vec3 interpolateHorizontally(vec2 inputPos, ivec2 inputPosFloor, int dy) {
-	vec3 ret = vec3(0.0);
-	float x = inputPos.x - float(inputPosFloor.x);
-
-	ret += A(x) * rgb(inputPosFloor.x - 1, inputPosFloor.y + dy);
-        ret += B(x) * rgb(inputPosFloor.x    , inputPosFloor.y + dy);
-        ret += C(x) * rgb(inputPosFloor.x + 1, inputPosFloor.y + dy);
-        ret += D(x) * rgb(inputPosFloor.x + 2, inputPosFloor.y + dy);
-	return ret;
-}
-
-vec4 process(vec2 outputPos) {
-	vec2 inputPos = outputPos / u_texelDelta - HALF_PIXEL;
-	ivec2 inputPosFloor = ivec2(inputPos);
-
-        vec3 ret = vec3(0.0);
-	float y = inputPos.y - float(inputPosFloor.y);
-	ret += A(y) * interpolateHorizontally(inputPos, inputPosFloor, -1);
-	ret += B(y) * interpolateHorizontally(inputPos, inputPosFloor,  0);
-	ret += C(y) * interpolateHorizontally(inputPos, inputPosFloor, +1);
-	ret += D(y) * interpolateHorizontally(inputPos, inputPosFloor, +2);
-	return vec4(ret / 324.0, 1.0);
-}
-
-void main()
-{
-        gl_FragColor.rgba = process(v_position);
-}

assets/shaders/upscale_mitchell_netravali.vsh

@@ -1,11 +0,0 @@
-attribute vec4 a_position;
-attribute vec2 a_texcoord0;
-
-varying vec2 v_position;
-
-void main()
-{
-  gl_Position = a_position;
-      
-  v_position = a_texcoord0;
-}