Create and validate a material

Before you start

• Hayba is installed and your agent is connected. See Getting started.
• You are in a scratch project, ideally under source control.
• Review each external edit is off. This guide creates assets, which the exact review cannot approve on this version. See What can be approved.

Prompt

Create a material M_Painted in /Game/Hayba/Materials with a vector parameter BaseColor (default mid grey) wired to Base Color and a scalar parameter Roughness (default 0.6) wired to Roughness. Validate the graph before compiling, then compile and report any errors. Make an instance MI_Painted_Red with BaseColor set to red, and apply it to the actor named Cube.

What the agent does

1. material_create creates the material.
2. material_add_node adds each expression, such as MaterialExpressionVectorParameter and MaterialExpressionScalarParameter.
3. material_connect_nodes wires each node to a material input or to another node.
4. material_validate checks the graph without compiling.
5. material_compile writes the material to disk, applies staged settings and returns translator errors and shader stats.
6. material_create_instance and material_set_param make the red instance.
7. material_apply assigns it to the actor.

Things worth knowing:

• Some broken wiring makes Unreal's shader translator assert, which takes the whole editor down: reroutes that lead nowhere, or links to output indices that do not exist. material_validate finds these without compiling, and material_compile runs the same checks and refuses to compile if any fail.
• Graph edits are not written to disk until material_compile. Call it once the graph is complete. The same goes for material functions.
• For a node with several outputs, such as a material function call, the agent must name the output pin. Hayba refuses the connection otherwise, because defaulting to the first output silently swaps outputs.
• material_get_info returns the full graph, parameters and a list of dead nodes that feed no output.
• To use the material on spline meshes, set used_with_spline_meshes with material_set_property before compiling.

Check the result

• Ask for material_get_info on the instance to confirm the parameter value.
• Ask the agent to frame the cube and capture the viewport. See Place actors and capture the viewport.
• Open M_Painted in the material editor.