float4x4 worldViewProj : WorldViewProjection;
        sampler2D image;
        float2 imageIncrement;

struct VertexShaderInput {
        float4 position : POSITION;
        float2 imageCoord : TEXCOORD0;
        };

struct PixelShaderInput {
        float4 position : POSITION;
        float2 imageCoord : TEXCOORD0;
        };

PixelShaderInput SobelVS(VertexShaderInput input) {
        PixelShaderInput output;
        output.position = mul(input.position, worldViewProj);
        output.imageCoord = input.imageCoord;
        return output;
        }

float lum(float4 c) {
        return dot(c.rgb, float3(0.3, 0.59, 0.11));
        }

float4 SobelPS(PixelShaderInput input) : COLOR {
        float2 imageCoord = input.imageCoord;
        float t00 = lum(tex2D(image, imageCoord + imageIncrement * float2(-1, -1)));
        float t10 = lum(tex2D(image, imageCoord + imageIncrement * float2( 0, -1)));
        float t20 = lum(tex2D(image, imageCoord + imageIncrement * float2( 1, -1)));
        float t01 = lum(tex2D(image, imageCoord + imageIncrement * float2(-1,  0)));
        float t21 = lum(tex2D(image, imageCoord + imageIncrement * float2( 1,  0)));
        float t02 = lum(tex2D(image, imageCoord + imageIncrement * float2(-1,  1)));
        float t12 = lum(tex2D(image, imageCoord + imageIncrement * float2( 0,  1)));
        float t22 = lum(tex2D(image, imageCoord + imageIncrement * float2( 1,  1)));
        float2 grad;
        grad.x = t00 + 2.0 * t01 + t02 - t20 - 2.0 * t21 - t22;
        grad.y = t00 + 2.0 * t10 + t20 - t02 - 2.0 * t12 - t22;
        float len = length(grad);
        return float4(len, len, len, 1.0);
        }

// #o3d VertexShaderEntryPoint SobelVS
        // #o3d PixelShaderEntryPoint SobelPS
        // #o3d MatrixLoadOrder RowMajor