examples: Improve 'crt-curvature.effect'

The code of this effect was quite dated and no longer up to my standards of coding, and lacking pretty much all comments that explain what things do. This meant that it was not a great example by default, and couldn't be used by new Effect creators as a reference.

Also the following settings were adjusted:
- 'Strength' now ranges from 0 to 200 %.
- 'Border Color' defaults to Opaque Black.
- 'Feathering' now ranges from 0 to 100 %.

data/examples/shaders/filter/crt-curvature.effect

@@ -1,32 +1,45 @@
-// Always provided by OBS
+// Copyright 2021 Michael Fabian Dirks <info@xaymar.com>
-uniform float4x4 ViewProj<
+//
-	bool automatic = true;
+// Redistribution and use in source and binary forms, with or without
-	string name = "View Projection Matrix";
+// modification, are permitted provided that the following conditions are met:
->;
+//
+// 1. Redistributions of source code must retain the above copyright notice,
+//    this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+// 3. Neither the name of the copyright holder nor the names of its contributors
+//    may be used to endorse or promote products derived from this software
+//    without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
 
-// Provided by Stream Effects
+#define IS_FILTER
-uniform float4 Time<
+#include "../base.effect"
-	bool automatic = true;
-	string name = "Time Array";
-	string description = "A float4 value containing the total time, rendering time and the time since the last tick. The last value is a random number between 0 and 1.";
->;
-uniform float4x4 Random<
-	bool automatic = true;
-	string name = "Random Array";
-	string description = "A float4x4 value containing random values between 0 and 1";
->;
-uniform texture2d InputA<
-	bool automatic = true;
->;
 
+//------------------------------------------------------------------------------
+// Uniforms
+//------------------------------------------------------------------------------
 uniform float _0_strength<
 	string name = "Strength";
+	string suffix = " %";
 	string field_type = "slider";
 	float minimum = 0.;
-	float maximum = 100.;
+	float maximum = 200.;
 	float step = 0.01;
 	float scale = 0.01;
 > = 33.33;
+
 uniform float4 _1_border<
 	string name = "Border Color";
 	string field_type = "slider";
@@ -34,66 +47,74 @@ uniform float4 _1_border<
 	float4 maximum = {100., 100., 100., 100.};
 	float4 step = {0.01, 0.01, 0.01, 0.01};
 	float4 scale = {0.01, 0.01, 0.01, 0.01};
-> = {0., 0., 0., 0.};
+> = {0., 0., 0., 100.};
+
 uniform float _2_feathering<
 	string name = "Feathering";
+	string suffix = " %";
 	string field_type = "slider";
-	float minimum = 0.01;
+	float minimum = 0.00;
 	float maximum = 100.;
 	float step = 0.01;
 	float scale = 0.01;
 > = 33.33;
 
-#define PI		3.1415926f
+//------------------------------------------------------------------------------
-#define TwoPI	6.2831853f
+// Technique: Combined Curvature
-#define HalfPI	1.5707963f
+//------------------------------------------------------------------------------
+float4 CombinedCurvature(VertexInformation vtx) : TARGET {
+	const float2 center = float2(0.5, 0.5);
 
-// ---------- Shader Code
+	// 1. Offset the texture coordinates towards the center.
-sampler_state def_sampler {
+	float2 cc = vtx.texcoord0.xy - center;
-	AddressU  = Clamp;
-	AddressV  = Clamp;
-	Filter    = Linear;
-};
 
-struct VertData {
+	// 2. Calculate the "distance" towards the edge by taking the dot product and multiplying it.
-	float4 pos : POSITION;
-	float2 uv  : TEXCOORD0;
-};
-
-VertData VSDefault(VertData v_in) {
-	VertData vert_out;
-	vert_out.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
-	vert_out.uv  = v_in.uv;
-	return vert_out;
-}
-
-float4 PSDefault(VertData v_in) : TARGET {
-	float2 center = {0.5, 0.5};
-
-	float2 cc = v_in.uv - center;
 	float dist = dot(cc, cc) * _0_strength;
-	float2 bentUV = v_in.uv + cc * (1.0 + dist) * dist;
 
+	// 3. Then use this to offset towards the center to create a curved look.
+	float2 bentUV = vtx.texcoord0.xy + cc * (1.0 + dist) * dist;
+
+	// 4. Check if the new generated UVs fall outside of the allowed area.
 	if ((bentUV.x <= 0. || bentUV.x >= 1.) || (bentUV.y <= 0. || bentUV.y >= 1.)) {
+		// If yes, return the configured border color.
 		return _1_border;
 	}
 
-	// Calculate border distance from texel center by ignoring the sign bit and normalizing the distance to 0..1.
+	// 5. Does the user want a smooth transition towards the border?
-	float2 borderDistance = (center - abs(bentUV - center)) / center;
+	if (_2_feathering >= .01) {
 		float2 borderArea = center * _2_feathering;
 
-	// Now apply a modifier so that we only get the border area.
+		// 1. Calculate how far away we are from the center.
-	borderDistance = (min(borderDistance - center * _2_feathering, 0) + borderArea) / borderArea;
+		float2 borderDistance = (center - abs(bentUV - center)) / center;
-	float borderFade = sin(borderDistance.x * HalfPI) * sin(borderDistance.y * HalfPI);
 
-	return lerp(_1_border, InputA.Sample(def_sampler, bentUV), borderFade);
+		// 2. Convert the calculated value into a useful distance.
+		borderDistance = (min(borderDistance - center * _2_feathering, 0) + borderArea) / borderArea;
+
+		// 3. Convert the distance into a proper fade value.
+		float borderFade = sin(borderDistance.x * PIb2) * sin(borderDistance.y * PIb2);
+
+		// 4. Return the mix of original and border color.
+		return lerp(_1_border, InputA.Sample(LinearClampSampler, bentUV), borderFade);
+	} else {
+		// Return the original color.
+		return InputA.Sample(LinearClampSampler, bentUV);
+	}
 }
 
 technique Draw
 {
 	pass
 	{
-		vertex_shader = VSDefault(v_in);
+		vertex_shader = DefaultVertexShader(vtx);
-		pixel_shader  = PSDefault(v_in); 
+		pixel_shader  = CombinedCurvature(vtx);
+	}
+}
+
+technique Combined
+{
+	pass
+	{
+		vertex_shader = DefaultVertexShader(vtx);
+		pixel_shader  = CombinedCurvature(vtx);
 	}
 }