https://community.esri.com/t5/arcgis-cityengine-questions/the-method-of-mapping-the-color-on-the-attribute/m-p/1688597#M11613 <P>&nbsp;</P><P>Hi,</P><P>I am trying to apply object-level RGB color data to building/facade rules, but I am encountering syntax errors related to attribute declaration and array usage.</P><P>Current situation:</P><UL><LI><P>I defined a custom attribute to store color data as numeric RGB values.</P></LI><LI><P>The attribute is intended to represent a 3-component color (values in 0–255).</P></LI><LI><P>I attempted to use array indexing (e.g., attr color = [255,255,255] and color[0]) to convert it into normalized RGB for use in the color() function.</P></LI></UL><P>Issues observed:</P><UL><LI><P>Declaring the attribute as a numeric array sometimes results in compilation errors.</P></LI><LI><P>Using indexed access on the attribute inside rule functions causes syntax errors.</P></LI><LI><P>The rule engine compiles only when the attribute is treated as a simple type (e.g., string or scalar).</P></LI></UL><P>Additionally:</P><UL><LI><P>I also attempted to convert RGB values to HSL for conditional styling, which further increased syntax complexity.</P></LI></UL><P>Questions:</P><UL><LI><P>What is the correct way to define and use multi-component numeric attributes in CGA?</P></LI><LI><P>Are fixed-length numeric arrays supported as attribute types?</P></LI><LI><P>If not, what is the recommended alternative for storing RGB values at the object level without causing syntax errors?</P></LI><LI><P>How should RGB → HSL conversion be implemented safely inside CGA rules?</P></LI></UL><P>The main problem appears to be related to attribute typing and syntax restrictions rather than the color conversion logic itself.</P><P>Any guidance on correct attribute definitions and color conversion handling would be appreciated.</P><P>Thank you.</P> Thu, 05 Mar 2026 03:07:13 GMT biaozeng 2026-03-05T03:07:13Z https://community.esri.com/t5/arcgis-cityengine-questions/the-method-of-mapping-the-color-on-the-attribute/m-p/1688597#M11613 <P>&nbsp;</P><P>Hi,</P><P>I am trying to apply object-level RGB color data to building/facade rules, but I am encountering syntax errors related to attribute declaration and array usage.</P><P>Current situation:</P><UL><LI><P>I defined a custom attribute to store color data as numeric RGB values.</P></LI><LI><P>The attribute is intended to represent a 3-component color (values in 0–255).</P></LI><LI><P>I attempted to use array indexing (e.g., attr color = [255,255,255] and color[0]) to convert it into normalized RGB for use in the color() function.</P></LI></UL><P>Issues observed:</P><UL><LI><P>Declaring the attribute as a numeric array sometimes results in compilation errors.</P></LI><LI><P>Using indexed access on the attribute inside rule functions causes syntax errors.</P></LI><LI><P>The rule engine compiles only when the attribute is treated as a simple type (e.g., string or scalar).</P></LI></UL><P>Additionally:</P><UL><LI><P>I also attempted to convert RGB values to HSL for conditional styling, which further increased syntax complexity.</P></LI></UL><P>Questions:</P><UL><LI><P>What is the correct way to define and use multi-component numeric attributes in CGA?</P></LI><LI><P>Are fixed-length numeric arrays supported as attribute types?</P></LI><LI><P>If not, what is the recommended alternative for storing RGB values at the object level without causing syntax errors?</P></LI><LI><P>How should RGB → HSL conversion be implemented safely inside CGA rules?</P></LI></UL><P>The main problem appears to be related to attribute typing and syntax restrictions rather than the color conversion logic itself.</P><P>Any guidance on correct attribute definitions and color conversion handling would be appreciated.</P><P>Thank you.</P> Thu, 05 Mar 2026 03:07:13 GMT https://community.esri.com/t5/arcgis-cityengine-questions/the-method-of-mapping-the-color-on-the-attribute/m-p/1688597#M11613 biaozeng 2026-03-05T03:07:13Z https://community.esri.com/t5/arcgis-cityengine-questions/the-method-of-mapping-the-color-on-the-attribute/m-p/1688615#M11614 <P>Solved through AI</P> Thu, 05 Mar 2026 07:33:34 GMT https://community.esri.com/t5/arcgis-cityengine-questions/the-method-of-mapping-the-color-on-the-attribute/m-p/1688615#M11614 biaozeng 2026-03-05T07:33:34Z