Function generateExpression

src/webgl/strands_glslBackend.js:266–404

(generationContext, dag, nodeID)

    generationContext.write(`return ${this.generateExpression(generationContext, dag, rootNodeID)};`);
  },
  generateExpression(generationContext, dag, nodeID) {
    const node = getNodeDataFromID(dag, nodeID);
    if (generationContext.tempNames?.[nodeID]) {
      return generationContext.tempNames[nodeID];
    }
    switch (node.nodeType) {
      case NodeType.LITERAL:
      if (node.baseType === BaseType.FLOAT) {
        return node.value.toFixed(4);
      }
      else {
        return node.value;
      }
      case NodeType.VARIABLE:
      // Track shared variable usage context
      if (generationContext.shaderContext && generationContext.strandsContext?.sharedVariables?.has(node.identifier)) {
        const sharedVar = generationContext.strandsContext.sharedVariables.get(node.identifier);
        if (generationContext.shaderContext === 'vertex') {
          sharedVar.usedInVertex = true;
        } else if (generationContext.shaderContext === 'fragment') {
          sharedVar.usedInFragment = true;
        }
      }

      // Detect instanceID usage in fragment context and rewrite to varying name
      if (node.identifier === this.instanceIdReference() && generationContext.shaderContext === 'fragment') {
        generationContext.strandsContext._instanceIDUsedInFragment = true;
        return INSTANCE_ID_VARYING_NAME;
      }

      return node.identifier;
      case NodeType.OPERATION:
      const useParantheses = node.usedBy.length > 0;
      if (node.opCode === OpCode.Nary.CONSTRUCTOR) {
        // TODO: differentiate casts and constructors for more efficient codegen.
        // if (node.dependsOn.length === 1 && node.dimension === 1) {
        //   return this.generateExpression(generationContext, dag, node.dependsOn[0]);
        // }
        if (node.baseType === BaseType.SAMPLER2D) {
          return this.generateExpression(generationContext, dag, node.dependsOn[0]);
        }
        const T = this.getTypeName(node.baseType, node.dimension);
        const deps = node.dependsOn.map((dep) => this.generateExpression(generationContext, dag, dep));
        return `${T}(${deps.join(', ')})`;
      }
      if (node.opCode === OpCode.Nary.FUNCTION_CALL) {
        const functionArgs = node.dependsOn.map(arg =>this.generateExpression(generationContext, dag, arg));
        return `${node.identifier}(${functionArgs.join(', ')})`;
      }
      if (node.opCode === OpCode.Nary.TERNARY) {
        const [condID, trueID, falseID] = node.dependsOn;
        const cond = this.generateExpression(generationContext, dag, condID);
        const trueExpr = this.generateExpression(generationContext, dag, trueID);
        const falseExpr = this.generateExpression(generationContext, dag, falseID);
        return `(${cond} ? ${trueExpr} : ${falseExpr})`;
      }
      if (node.opCode === OpCode.Binary.MEMBER_ACCESS) {
        const [lID, rID] = node.dependsOn;