VOGONS


First post, by Spa8nky

User metadata
Rank Newbie
Rank
Newbie

Hi folks,

I've written an HLSL shader for producing evenly spaced scanlines on an HDTV (tested in 1080p):

/*
Copyright (C) 2010 Rhys J. Perkins

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

//
// 2D Scale Effect File
//
// Point Sampling
//

#define LINES_ON 1.0
#define LINES_OFF 1.0
#define OFF_INTENSITY 0.5

#include "Scaling.inc"

// The name of this effect
string name : NAME = "Point Sampling";
float scaling : SCALING = 2.0;

//
// Techniques
//

// combineTechnique: Final combine steps. Outputs to destination frame buffer
string combineTechique : COMBINETECHNIQUE = "Point";

//
// Vertex Shader Output
//

struct VS_OUTPUT
{
float4 Position : POSITION;
float2 UV : TEXCOORD0;
};


//
// Vertex Shader
//

VS_OUTPUT VS(float3 Position : POSITION, float2 TexCoord : TEXCOORD0)
{
VS_OUTPUT Out = (VS_OUTPUT)0;

Show last 41 lines
	Out.Position = mul(float4(Position, 1), WorldViewProjection);   // Matrix multipliy
Out.UV = TexCoord;

return Out;
}


//
// Pixel Shader
//

float4 PS (in VS_OUTPUT input) : COLOR
{
// Adjust pixelRatio in multiples of 0.9 (derived from 16:9 / 16:10 ratio)
// This will adjust the thickness of the scanlines
float pixelRatio = 2.7; //1.8; //0.9;

float intensity = (input.UV.y * SourceDims.y * pixelRatio) % (LINES_ON + LINES_OFF);
intensity = intensity < LINES_ON ? 1.0 : OFF_INTENSITY;

return tex2D(SourceSampler, input.UV) * intensity;
}


//
// Technique
//

technique Point
{
pass P0
{
// shaders
VertexShader = compile vs_2_0 VS();
PixelShader = compile ps_2_0 PS();
AlphaBlendEnable = FALSE;
ColorWriteEnable = RED|GREEN|BLUE|ALPHA;
SRGBWRITEENABLE = FALSE;
}
}

DosBox is unable to produce evenly spaced scalines using the tv2x shader in fullscreen mode on my HDTV. This shader fixes that.

It should be noted that I have tested this using ykhwong's 2010-12-25 SVN build for Windows.

I hope somebody else finds it useful.

Thanks,

Rhys

Reply 1 of 1, by Spa8nky

User metadata
Rank Newbie
Rank
Newbie

Had a chance to play with this for 5 mins today. It should be noted that this shader can be adapted to any monitor resolution.

Change the following line:

float pixelRatio = 2.7; //1.8; //0.9; 

to:

float pixelRatio = yRes / 240.0f;

Where 'yRes' is your monitor's y resolution (as a float).

You can scale the pixelRatio after calculation also:

pixelRatio *= 1.5f;