wehub-resource-sync
82 lines
3.3 KiB
C#
82 lines
3.3 KiB
C#
using T3.Core.DataTypes.ShaderGraph;
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namespace Lib.field.use;
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[Guid("48136477-cb34-416c-a968-7c9d82da9d9b")]
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internal sealed class SdfToVector : Instance<SdfToVector>
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, IGraphNodeOp
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{
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[Output(Guid = "8055c3e2-0830-4795-ad60-16d8716209fc")]
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public readonly Slot<ShaderGraphNode> Result = new();
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public SdfToVector()
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{
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ShaderNode = new ShaderGraphNode(this, null, InputField);
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Result.Value = ShaderNode;
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Result.UpdateAction += Update;
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}
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private void Update(EvaluationContext context)
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{
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ShaderNode.Update(context);
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ShaderNode.FlagCodeChanged();
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}
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public ShaderGraphNode ShaderNode { get; }
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/// <remarks>
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/// This method is more complex than might be obvious:
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/// - We need to sample the field at 4 + 1 positions.
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/// - But we _only_ want to include incoming shader code once.
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/// - The only solution is to define and wrap the shader code inside a method.
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/// - But the incoming shader code must be collected in THIS call through CollectEmbeddedShaderCode()
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/// - To separate the sub shader code for our method, we have to introduce a stack of StringBuilders to
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/// push and keep the previous StringBuilders and then pop and convert the temporary ones into a string.
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/// - This result can then be used to define an instance method with that code...
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/// - which can then be called from the actual shader lines.
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///
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/// This hasn't been extensively tested. But it should be.
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/// </remarks>
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bool IGraphNodeOp.TryBuildCustomCode(CodeAssembleContext c)
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{
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var fields = ShaderNode.InputNodes;
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if (fields.Count == 0)
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return true;
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c.PushMethod("GetDistance");
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var inputField = fields[0];
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inputField?.CollectEmbeddedShaderCode(c);
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var nestedCode = c.PopMethod();
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c.Definitions.Append($$"""
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float {{c}}GetSdfDistance(float3 p3)
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{
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float4 p{{c}} = float4(p3, 0);
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float4 f{{c}} = 1;
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{{nestedCode}}
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return f{{c}}.w;
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}
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""");
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var offset = $"{ShaderNode}LookUpDistance";
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c.AppendCall($"""
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f{c}.xyz = normalize(
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{c}GetSdfDistance(p{c}.xyz + float3({offset}, -{offset}, -{offset})) * float3(1, -1, -1) +
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{c}GetSdfDistance(p{c}.xyz + float3(-{offset}, {offset}, -{offset})) * float3(-1, 1, -1) +
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{c}GetSdfDistance(p{c}.xyz + float3(-{offset}, -{offset}, {offset})) * float3(-1, -1, 1) +
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{c}GetSdfDistance(p{c}.xyz + float3({offset}, {offset}, {offset})) * float3(1, 1, 1));
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f{c}.w = GetSdfDistance(p{c}.xyz);
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""");
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return true;
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}
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[Input(Guid = "d6664c35-040a-4021-ac37-aa7eaaae2b65")]
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public readonly InputSlot<ShaderGraphNode> InputField = new();
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[GraphParam]
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[Input(Guid = "2ea69efd-a01b-4a7f-8f87-31c8dfefcad5")]
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public readonly InputSlot<float> LookUpDistance = new();
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} |