add ossc like shader (#421)

* add ossc-like shader

scanlines/ossc.slangp

@@ -0,0 +1,4 @@
+shaders = 1
+
+shader0 = shaders/ossc.slang
+scale_type0 = viewport

scanlines/shaders/ossc.slang

@@ -0,0 +1,146 @@
+#version 450
+
+
+// An OSSC-like shader
+// By DariusG @May/2023
+
+layout(push_constant) uniform Push
+{
+	vec4 SourceSize;
+	vec4 OriginalSize;
+	vec4 OutputSize;
+	uint FrameCount;
+	float OVERSCAN,ASPECTx,ASPECTy, LINES, L1, L2,L3,L4,L5,TATE, HYBRID;
+} params;
+
+#pragma parameter LINES "Lines" 4.0 2.0 5.0 1.0
+#define LINES params.LINES
+
+#pragma parameter TATE "TATE mode"  0.0 0.0 1.0 1.0
+#define TATE params.TATE
+
+#pragma parameter L1 "Line 1 Scanline Strength %" 0.25 0.0 1.0 0.01
+#define L1 params.L1
+
+#pragma parameter L2 "Line 2 Scanline Strength %" 0.0 0.0 1.0 0.01
+#define L2 params.L2
+
+#pragma parameter L3 "Line 3 Scanline Strength %" 0.0 0.0 1.0 0.01
+#define L3 params.L3
+
+#pragma parameter L4 "Line 4 Scanline Strength %" 0.4 0.0 1.0 0.01
+#define L4 params.L4
+
+#pragma parameter L5 "Line 5 Scanline Strength %" 0.5 0.0 1.0 0.01
+#define L5 params.L5
+
+#pragma parameter HYBRID "Scanline Hybrid Blend % (depend on pixel overlayed)" 0.0 0.0 1.0 0.01
+#define HYBRID params.HYBRID
+
+#pragma parameter OVERSCAN "Overscan" 0.0 0.0 1.0 1.0 
+#define OVERSCAN params.OVERSCAN
+
+#pragma parameter something "--Set Retroarch Aspect to FULL--" 0.0 0.0 0.0 0.0
+
+#pragma parameter ASPECTx "Aspect Ratio X" 4.0 1.0 32.0 1.0 
+#define ASPECTx params.ASPECTx
+
+#pragma parameter ASPECTy "Aspect Ratio Y" 3.0 1.0 32.0 1.0 
+#define ASPECTy params.ASPECTy
+
+#define OutputSize params.OutputSize
+#define SourceSize params.SourceSize
+#define OriginalSize params.OriginalSize
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+	mat4 MVP;
+	
+} global;
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 2) uniform sampler2D Source;
+
+vec2 Overscan(vec2 pos, float dx, float dy){
+	pos=pos*2.0-1.0;    
+	pos*=vec2(dx/(ASPECTx/ASPECTy/OutputSize.x*OutputSize.y),dy);
+	return pos*0.5 + 0.5;
+} 
+
+float scanline5(float y, float lm)
+{
+	float l = 1.0/LINES;
+	float m = fract(y*l);
+	if (m<l) return 1.0-L1*(1.0-lm*HYBRID);
+	else if (m<2.0*l) return 1.0-L2*(1.0-lm*HYBRID);
+	else if (m<3.0*l) return 1.0-L3*(1.0-lm*HYBRID);
+	else if (m<4.0*l) return 1.0-L4*(1.0-lm*HYBRID);
+	else return 1.0-L5*(1.0-lm*HYBRID);
+}
+
+float scanline4(float y, float lm)
+{
+	float l = 1.0/LINES;
+	float m = fract(y*l);
+	if (m<l) return 1.0-L1*(1.0-lm*HYBRID);
+	else if (m<2.0*l) return 1.0-L2*(1.0-lm*HYBRID);
+	else if (m<3.0*l) return 1.0-L3*(1.0-lm*HYBRID);
+	else return   1.0-L4*(1.0-lm*HYBRID);
+	
+}
+float scanline3(float y, float lm)
+{
+	float l = 1.0/LINES;
+	float m = fract(y*lm);
+	if (m<l) return 1.0-L1*(1.0-lm*HYBRID);
+	else if (m<2.0*l) return 1.0-L2*(1.0-lm*HYBRID);
+	else return   1.0-L3*(1.0-lm*HYBRID);
+	
+}
+
+float scanline2(float y, float lm)
+{
+	float l = 1.0/LINES;
+	float m = fract(y*l);
+	if (m<l) return 1.0-L1*(1.0-lm*HYBRID);
+	else return 1.0-L2*(1.0-lm*HYBRID);
+		
+}
+
+void main()
+{
+	vec2 texcoord = vTexCoord.xy;
+	vec2 ofactor = OutputSize.xy/OriginalSize.xy;
+	vec2 intfactor;
+	if (OVERSCAN == 0.0) intfactor = floor(ofactor); else intfactor = ceil(ofactor);
+	vec2 diff = ofactor/intfactor;
+	float scan = diff.y;
+	texcoord = Overscan(texcoord, scan, scan);
+
+   vec2 OGL2Pos = vTexCoord.xy*OutputSize.xy;
+   if (TATE == 1.0) OGL2Pos = vec2(OGL2Pos.y,OGL2Pos.x);
+	
+	vec3 res = texture(Source, texcoord).rgb;
+	vec3 lumweight = vec3 (0.2126,0.7152,0.0722);
+	float lum = dot(res, lumweight);
+
+	if (LINES == 5.0) {res *= scanline5(OGL2Pos.y, lum);}
+	else if (LINES == 4.0){res *= scanline4(OGL2Pos.y,lum);}
+	else if (LINES == 3.0){res *= scanline3(OGL2Pos.y,lum);}
+	else if (LINES == 2.0){res *= scanline2(OGL2Pos.y,lum);}
+
+   FragColor = vec4(res,1.0);
+}