//Cg

void vshader(
    float4 vtx_position : POSITION,
    float2 vtx_texcoord0 : TEXCOORD0,
    out float4 l_position : POSITION,
    out float2 l_texcoord0 : TEXCOORD0,
    out float2 l_texcoord1 : TEXCOORD1,
    uniform float4 texpad_tex,
    uniform float4x4 mat_modelproj)
{
    l_position=mul(mat_modelproj, vtx_position);
    l_texcoord0 = vtx_position.xz * texpad_tex.xy + texpad_tex.xy;
    l_texcoord1 = l_position.xy;
}

void fshader(float2 l_texcoord0 : TEXCOORD0,
             float2 l_texcoord1 : TEXCOORD1,
             out float4 o_color : COLOR,
             uniform sampler2D k_tex : TEXUNIT0)
{
    float4 c = tex2D(k_tex, l_texcoord0);

    // basic black and white effet
    float bright = (c.x + c.y + c.z)/3;

    // create a vignette to simulate old optics
    float d = distance(float2(0.0, 0.0), l_texcoord1);
    float OuterVignetting = 1.6;
    float InnerVignetting = 0.6;
    float vignetting = clamp((OuterVignetting - d) / (OuterVignetting - InnerVignetting), 0.0, 1.0);
    // non-linear fade to prevent ugly border effect
    float diff = 1.0 - vignetting;
    bright *= 1.0 - (diff * diff);

    o_color = float4(bright, bright, bright, 1);
}