"Print a value" custom function node code for Unity ShaderGraph

DebugNode.hlsl

// Quick try at doing a "print value" node for Unity ShaderGraph.
// Tested on Unity 2019.2.17 with ShaderGraph 6.9.2.
//
// Use with CustomFunction node, with two inputs:
// - Vector1 Value, the value to display,
// - Vector2 UV, the UVs of area to display at.
// And one output:
// - Vector4 Color, the color.
// Function name is DoDebug.

// "print in shader" based on this excellent ShaderToy by @P_Malin:
// https://www.shadertoy.com/view/4sBSWW

float DigitBin(const int x)
{
    return x==0?480599.0:x==1?139810.0:x==2?476951.0:x==3?476999.0:x==4?350020.0:x==5?464711.0:x==6?464727.0:x==7?476228.0:x==8?481111.0:x==9?481095.0:0.0;
}

float PrintValue(float2 vStringCoords, float fValue, float fMaxDigits, float fDecimalPlaces)
{
    if ((vStringCoords.y < 0.0) || (vStringCoords.y >= 1.0))
        return 0.0;

    bool bNeg = (fValue < 0.0);
    fValue = abs(fValue);

    float fLog10Value = log2(abs(fValue)) / log2(10.0);
    float fBiggestIndex = max(floor(fLog10Value), 0.0);
    float fDigitIndex = fMaxDigits - floor(vStringCoords.x);
    float fCharBin = 0.0;
    if (fDigitIndex > (-fDecimalPlaces - 1.01))
    {
        if(fDigitIndex > fBiggestIndex)
        {
            if((bNeg) && (fDigitIndex < (fBiggestIndex+1.5))) fCharBin = 1792.0;
        }
        else
        {
            if(fDigitIndex == -1.0)
            {
                if(fDecimalPlaces > 0.0) fCharBin = 2.0;
            }
            else
            {
                float fReducedRangeValue = fValue;
                if(fDigitIndex < 0.0) { fReducedRangeValue = frac( fValue ); fDigitIndex += 1.0; }
                float fDigitValue = (abs(fReducedRangeValue / (pow(10.0, fDigitIndex))));
                fCharBin = DigitBin(int(floor(fmod(fDigitValue, 10.0))));
            }
        }
    }
    return floor(fmod((fCharBin / pow(2.0, floor(frac(vStringCoords.x) * 4.0) + (floor(vStringCoords.y * 5.0) * 4.0))), 2.0));
}

float PrintValue(const in float2 fragCoord, const in float2 vPixelCoords, const in float2 vFontSize, const in float fValue, const in float fMaxDigits, const in float fDecimalPlaces)
{
    float2 vStringCharCoords = (fragCoord.xy - vPixelCoords) / vFontSize;
    return PrintValue( vStringCharCoords, fValue, fMaxDigits, fDecimalPlaces );
}

void DoDebug_float(float val, float2 uv, out float4 res)
{
    res = float4(0.3,0.2,0.1,1);
    res = PrintValue(uv*200, float2(10,100), float2(8,15), val, 10, 3);
}

Thanks @bestknighter, that's great work. I'll use your forked version.

Small issue...

@emilioparker are you using my fork? This version has some small bugs with float precision and I made a workaround on my fork.

King

Building upon the work of @aras-p and @bestknighter, I've developed a DebugSubGraph to streamline the process of setting up debug nodes .

Building upon the work of @aras-p and @bestknighter, I've developed a DebugSubGraph to streamline the process of setting up debug nodes .

Wow! Amazing stuff! Thank you for crediting us! That's very much appreciated.

I am new to shaders, and printing values seems like an awesome tool, but one thing that puzzles me is that the printing using the debugsubgraph depends on position. When I attach a position node, I get nonsense numbers. This makes sense, since the position node changes depending on where you are, but I figured I'd share since this interaction is hilarious and this may help other users. Also if anyone knows how to use this tool to debug things with position nodes or view direction nodes, let me know

I am new to shaders, and printing values seems like an awesome tool, but one thing that puzzles me is that the printing using the debugsubgraph depends on position. When I attach a position node, I get nonsense numbers. This makes sense, since the position node changes depending on where you are, but I figured I'd share since this interaction is hilarious and this may help other users. Also if anyone knows how to use this tool to debug things with position nodes or view direction nodes, let me know

Hahaha yep, that's totally by design.
The only way I can think of achieving what you want is by some kind of way making Position node (or some other node between it and Multiply) output a single value. Just like using a Texture Sampler with locked UV coordinates instead of the vertex/fragment UV. Maybe outputting the world position of the object instead of the vertex/fragment? I'm not sure how doable this is. I can't think of anything beyond this right now, sorry about that.