BabylonJS/Babylon.js · error · Error

Invalid channel input configuration

Error message

Invalid channel input configuration

What it means

MergeTexturesAsync decides per channel whether the input is a texture input, a constant input, or absent. This error is thrown when the channel object is present but matches neither recognized input shape — i.e. a malformed configuration object.

Source

Thrown at packages/dev/core/src/Materials/Textures/textureMerger.ts:128

                if (channel.sourceChannel < 0 || channel.sourceChannel > 3) {
                    throw new Error("Source channel must be between 0 and 3 (R, G, B, A)");
                }

                // Find or add texture to inputs
                let textureIndex = textureInputs.indexOf(channel.texture);
                if (textureIndex === -1) {
                    textureIndex = textureInputs.length;
                    textureInputs.push(channel.texture);
                }
                textureInputMap[channelIndex] = textureIndex;
            } else if (IsConstantInput(channel)) {
                // Validate constant value
                if (channel.value < 0 || channel.value > 1) {
                    throw new Error("Constant value must be between 0.0 and 1.0");
                }
                textureInputMap[channelIndex] = -1;
            } else {
                throw new Error("Invalid channel input configuration");
            }
        } else {
            textureInputMap[channelIndex] = -1;
        }
    }

    // Determine output size
    let outputSize = config.outputSize;
    if (!outputSize && textureInputs.length > 0) {
        // Use the largest texture size
        let maxSize = 0;
        for (const texture of textureInputs) {
            const size = texture.getSize();
            const currentSize = Math.max(size.width, size.height);
            if (currentSize > maxSize) {
                maxSize = currentSize;
                outputSize = size.width === size.height ? maxSize : size;
            }

View on GitHub (pinned to 0592b347b8)

Solutions

1. Ensure each non-null channel is exactly { texture: BaseTexture, sourceChannel: 0-3 } or { value: 0-1 }.
2. Log the channel object before calling to confirm the property names and that the intended field is not undefined.
3. Use the documented helper (e.g. CreateMergedAnisotropyTexture) instead of building raw channel configs by hand.

Example fix

// before
{ tex: roughnessTexture, sourceChannel: 2 }
// after
{ texture: roughnessTexture, sourceChannel: 2 }

type TextureInput = { texture: BaseTexture; sourceChannel: number };
type ConstantInput = { value: number };
function isValidChannel(c: unknown): c is TextureInput | ConstantInput {
  if (c == null || typeof c !== "object") return false;
  const o = c as any;
  return ("texture" in o && o.texture != null) || typeof o.value === "number";
}

function isTextureInput(c: unknown): c is { texture: BaseTexture; sourceChannel: number } {
  return !!c && typeof c === "object" && "texture" in c && (c as any).texture != null;
}

try {
  const tex = await MergeTexturesAsync(channels, w, h, scene);
} catch (e) {
  if (String(e.message).includes("Invalid channel input configuration")) {
    console.error("Each channel must be {texture, sourceChannel} or {value}:", channels);
  }
}

When it happens

Trigger: Passing a channel object to MergeTexturesAsync that is neither a texture input (has .texture) nor a constant input (has .value) — e.g. { texture: undefined, value: undefined }, a wrong property name, or an object created with a broken factory.

Common situations: Typos like { textureId } or { tex } instead of { texture }, passing a raw Texture instead of a channel descriptor, deserialized config that lost its shape, API version change in the merger input types.

Related errors

• Cannot compare ${a} and ${b}
• Cannot get NaN of ${a}
• Cannot get isInf of ${a}
• Cannot perform bitwise AND on ${a} and ${b}
• Cannot perform bitwise OR on ${a} and ${b}

AI-assisted analysis of BabylonJS/Babylon.js@0592b347b8 (2026-08-30). Data as JSON: /api/errors/d7332bb3173b7991. Report an issue: GitHub.