Error X3650 when compiling shader in XNA

Question

I'm attempting to convert the XBDEV.NET Mosaic Shader for use in my XNA project and having trouble. The compiler errors out because of the half globals.

At first I tried replacing the globals and just writing the variables explicitly in the code, but that garbles the Output. Next I tried replacing all the half with float vars, but that still garbles the resulting Image.

I call the effect file from SpriteBatch.Begin().

Is there a way to convert this shader to the new pixel shader conventions? Are there any good tutorials for this topic?

Here is the shader file for reference:

/*****************************************************************************/
/*
File: tiles.fx
Details: Modified version of the NVIDIA Composer FX Demo Program 2004
Produces a tiled mosaic effect on the output.

Requires:  Vertex Shader 1.1
           Pixel Shader 2.0     


Modified by: [email protected] (www.xbdev.net)

*/
/*****************************************************************************/

float4 ClearColor : DIFFUSE = { 0.0f, 0.0f, 0.0f, 1.0f};
float ClearDepth = 1.0f;

/******************************** TWEAKABLES *********************************/
half NumTiles = 40.0;

half Threshhold = 0.15;

half3 EdgeColor = {0.7f, 0.7f, 0.7f};

/*****************************************************************************/

texture SceneMap : RENDERCOLORTARGET < 
float2 ViewportRatio = { 1.0f, 1.0f };
int MIPLEVELS = 1;
string format = "X8R8G8B8";
string UIWidget = "None";
>;

sampler SceneSampler = sampler_state {
texture = <SceneMap>;
AddressU  = CLAMP;        
AddressV  = CLAMP;
MIPFILTER = NONE;
MINFILTER = LINEAR;
MAGFILTER = LINEAR;
};


/***************************** DATA STRUCTS **********************************/

struct vertexInput {
half3 Position : POSITION;
half3 TexCoord : TEXCOORD0;
};

/* data passed from vertex shader to pixel shader */
struct vertexOutput {
half4 HPosition : POSITION;
half2 UV        : TEXCOORD0;
};

 /******************************* Vertex shader *******************************/

vertexOutput VS_Quad( vertexInput IN)
{
vertexOutput OUT = (vertexOutput)0;
OUT.HPosition = half4(IN.Position, 1);
OUT.UV = IN.TexCoord.xy; 
return OUT;
}

/********************************** pixel shader *****************************/

half4 tilesPS(vertexOutput IN) : COLOR {
half size = 1.0/NumTiles;
half2 Pbase = IN.UV - fmod(IN.UV,size.xx);
half2 PCenter = Pbase + (size/2.0).xx;

half2 st = (IN.UV - Pbase)/size;
half4 c1 = (half4)0;
half4 c2 = (half4)0;
half4 invOff = half4((1-EdgeColor),1);
if (st.x > st.y) { c1 = invOff; }
half threshholdB =  1.0 - Threshhold;
if (st.x > threshholdB) { c2 = c1; }
if (st.y > threshholdB) { c2 = c1; }
half4 cBottom = c2;
c1 = (half4)0;
c2 = (half4)0;
if (st.x > st.y) { c1 = invOff; }
if (st.x < Threshhold) { c2 = c1; }
if (st.y < Threshhold) { c2 = c1; }
half4 cTop = c2;

half4 tileColor = tex2D(SceneSampler,PCenter);
half4 result = tileColor + cTop - cBottom;
return result;
}

/*****************************************************************************/

technique tiles
{
pass p0 
{       
    VertexShader = compile vs_1_1 VS_Quad();
    ZEnable = false;
    ZWriteEnable = false;
    CullMode = None;
    PixelShader = compile ps_2_0 tilesPS();
}
}

Answer 1

I believe you should be able to fix this simply by replacing all the half variables by float variables.
The only difference is that a half is a 16-bit float value while a true float is 32-bits.