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aydinfer

Spline MCP Server

by aydinfer
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JavaScript
Remote

generateAnimationCode

Create animation code for 3D objects in Spline scenes to rotate, move, scale, or change colors with customizable duration, easing, and looping options.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
sceneIdYesScene ID
objectIdYesObject ID
animationTypeYesAnimation type
durationNoAnimation duration (ms)
easingNoAnimation easingeaseInOut
loopNoWhether to loop the animation
paramsNoAnimation-specific parameters

Implementation Reference

  • src/tools/runtime-tools.js:73-122 (registration)
    Registration of the 'generateAnimationCode' tool including schema definition and handler function that delegates to runtimeManager
    server.tool(
  'generateAnimationCode',
  {
    sceneId: z.string().min(1).describe('Scene ID'),
    objectId: z.string().min(1).describe('Object ID'),
    animationType: z.enum(['rotate', 'move', 'scale', 'color']).describe('Animation type'),
    duration: z.number().int().min(100).default(1000).describe('Animation duration (ms)'),
    easing: z.enum(['linear', 'easeIn', 'easeOut', 'easeInOut']).default('easeInOut')
      .describe('Animation easing'),
    loop: z.boolean().default(false).describe('Whether to loop the animation'),
    params: z.record(z.any()).optional().describe('Animation-specific parameters'),
  },
  async ({ sceneId, objectId, animationType, duration, easing, loop, params }) => {
    try {
      const animationParams = {
        animationType,
        duration,
        easing,
        loop,
        ...(params && params),
      };
      
      const code = runtimeManager.generateObjectInteractionCode(
        sceneId, 
        objectId, 
        'animation', 
        animationParams
      );
      
      return {
        content: [
          { 
            type: 'text', 
            text: code 
          }
        ]
      };
    } catch (error) {
      return {
        content: [
          { 
            type: 'text', 
            text: `Error generating animation code: ${error.message}` 
          }
        ],
        isError: true
      };
    }
  }
);
  • src/tools/runtime-tools.js:85-121 (handler)
    The MCP tool handler that processes inputs and calls runtimeManager.generateObjectInteractionCode to produce animation code
    async ({ sceneId, objectId, animationType, duration, easing, loop, params }) => {
  try {
    const animationParams = {
      animationType,
      duration,
      easing,
      loop,
      ...(params && params),
    };
    
    const code = runtimeManager.generateObjectInteractionCode(
      sceneId, 
      objectId, 
      'animation', 
      animationParams
    );
    
    return {
      content: [
        { 
          type: 'text', 
          text: code 
        }
      ]
    };
  } catch (error) {
    return {
      content: [
        { 
          type: 'text', 
          text: `Error generating animation code: ${error.message}` 
        }
      ],
      isError: true
    };
  }
}
  • src/tools/runtime-tools.js:76-84 (schema)
    Zod schema defining input parameters for the generateAnimationCode tool
      sceneId: z.string().min(1).describe('Scene ID'),
  objectId: z.string().min(1).describe('Object ID'),
  animationType: z.enum(['rotate', 'move', 'scale', 'color']).describe('Animation type'),
  duration: z.number().int().min(100).default(1000).describe('Animation duration (ms)'),
  easing: z.enum(['linear', 'easeIn', 'easeOut', 'easeInOut']).default('easeInOut')
    .describe('Animation easing'),
  loop: z.boolean().default(false).describe('Whether to loop the animation'),
  params: z.record(z.any()).optional().describe('Animation-specific parameters'),
},
  • src/utils/runtime-manager.js:453-547 (helper)
    Core helper function in RuntimeManager that generates the specific animation code based on animationType, duration, easing, and loop parameters
          case 'animation':
        const { 
          animationType = 'rotate',
          duration = 1000,
          easing = 'easeInOut',
          loop = false
        } = params;
        
        let animationCode = '';
        
        if (animationType === 'rotate') {
          animationCode = `
  // Rotate animation
  const startRotation = { ...obj.rotation };
  const targetRotation = { 
    x: startRotation.x + Math.PI * 2,  // Full 360° rotation
    y: startRotation.y,
    z: startRotation.z
  };
  
  obj.rotation.x = startRotation.x + (targetRotation.x - startRotation.x) * progress;`;
        } else if (animationType === 'move') {
          animationCode = `
  // Move animation
  const startPosition = { ...obj.position };
  const targetPosition = { 
    x: startPosition.x,
    y: startPosition.y + 1,  // Move up by 1 unit
    z: startPosition.z
  };
  
  obj.position.x = startPosition.x + (targetPosition.x - startPosition.x) * progress;
  obj.position.y = startPosition.y + (targetPosition.y - startPosition.y) * progress;
  obj.position.z = startPosition.z + (targetPosition.z - startPosition.z) * progress;`;
        } else if (animationType === 'scale') {
          animationCode = `
  // Scale animation
  const startScale = { ...obj.scale };
  const targetScale = { 
    x: startScale.x * 1.5,  // Scale up by 50%
    y: startScale.y * 1.5,
    z: startScale.z * 1.5
  };
  
  obj.scale.x = startScale.x + (targetScale.x - startScale.x) * progress;
  obj.scale.y = startScale.y + (targetScale.y - startScale.y) * progress;
  obj.scale.z = startScale.z + (targetScale.z - startScale.z) * progress;`;
        }
        
        let easingFunction = '';
        
        if (easing === 'linear') {
          easingFunction = 'const ease = progress;';
        } else if (easing === 'easeIn') {
          easingFunction = 'const ease = progress * progress;';
        } else if (easing === 'easeOut') {
          easingFunction = 'const ease = 1 - Math.pow(1 - progress, 2);';
        } else { // easeInOut
          easingFunction = 'const ease = progress < 0.5 ? 2 * progress * progress : 1 - Math.pow(-2 * progress + 2, 2) / 2;';
        }
        
        codeSnippet = `
// Animate object
const obj = spline.findObjectById('${objectId}');
let startTime = null;
const duration = ${duration}; // milliseconds
let animationFrame;

function animate(timestamp) {
  if (!startTime) startTime = timestamp;
  const elapsed = timestamp - startTime;
  let progress = Math.min(elapsed / duration, 1);
  
  // Apply easing
  ${easingFunction}
  progress = ease;
  
${animationCode}
  
  if (progress < 1) {
    animationFrame = requestAnimationFrame(animate);
  } else if (${loop}) {
    // Reset for looping
    startTime = null;
    animationFrame = requestAnimationFrame(animate);
  }
}

// Start animation
animationFrame = requestAnimationFrame(animate);

// To stop animation early:
// cancelAnimationFrame(animationFrame);
`;
        break;
  • src/utils/runtime-manager.js:212-567 (helper)
    Full generateObjectInteractionCode method called by the tool handler, with switch case for 'animation' containing the animation logic
      generateObjectInteractionCode(sceneId, objectId, action, params = {}) {
    const sceneUrl = `https://prod.spline.design/${sceneId}/scene.splinecode`;
    
    let codeSnippet = '';
    
    switch (action) {
      case 'move':
        const { x = 0, y = 0, z = 0 } = params;
        codeSnippet = `
// Move object
const obj = spline.findObjectById('${objectId}');
obj.position.x = ${x};
obj.position.y = ${y};
obj.position.z = ${z};

// Animate movement smoothly (alternative approach)
let startTime = null;
const duration = 1000; // 1 second
const startPos = { ...obj.position };
const targetPos = { x: ${x}, y: ${y}, z: ${z} };

function animateMove(timestamp) {
  if (!startTime) startTime = timestamp;
  const elapsed = timestamp - startTime;
  const progress = Math.min(elapsed / duration, 1);
  
  // Use easing function (ease-out-cubic)
  const easeOut = 1 - Math.pow(1 - progress, 3);
  
  obj.position.x = startPos.x + (targetPos.x - startPos.x) * easeOut;
  obj.position.y = startPos.y + (targetPos.y - startPos.y) * easeOut;
  obj.position.z = startPos.z + (targetPos.z - startPos.z) * easeOut;
  
  if (progress < 1) {
    requestAnimationFrame(animateMove);
  }
}

// Uncomment to use animation instead of direct positioning
// requestAnimationFrame(animateMove);
`;
        break;
        
      case 'rotate':
        const { rotX = 0, rotY = 0, rotZ = 0 } = params;
        codeSnippet = `
// Rotate object
const obj = spline.findObjectById('${objectId}');
obj.rotation.x = ${rotX} * Math.PI / 180; // Convert degrees to radians
obj.rotation.y = ${rotY} * Math.PI / 180;
obj.rotation.z = ${rotZ} * Math.PI / 180;

// Animate rotation smoothly (alternative approach)
let startTime = null;
const duration = 1000; // 1 second
const startRot = { ...obj.rotation };
const targetRot = { 
  x: ${rotX} * Math.PI / 180,
  y: ${rotY} * Math.PI / 180,
  z: ${rotZ} * Math.PI / 180
};

function animateRotation(timestamp) {
  if (!startTime) startTime = timestamp;
  const elapsed = timestamp - startTime;
  const progress = Math.min(elapsed / duration, 1);
  
  // Use easing function (ease-in-out)
  const easeInOut = progress < 0.5 ? 2 * progress * progress : 1 - Math.pow(-2 * progress + 2, 2) / 2;
  
  obj.rotation.x = startRot.x + (targetRot.x - startRot.x) * easeInOut;
  obj.rotation.y = startRot.y + (targetRot.y - startRot.y) * easeInOut;
  obj.rotation.z = startRot.z + (targetRot.z - startRot.z) * easeInOut;
  
  if (progress < 1) {
    requestAnimationFrame(animateRotation);
  }
}

// Uncomment to use animation instead of direct rotation
// requestAnimationFrame(animateRotation);
`;
        break;
        
      case 'scale':
        const { scaleX = 1, scaleY = 1, scaleZ = 1 } = params;
        codeSnippet = `
// Scale object
const obj = spline.findObjectById('${objectId}');
obj.scale.x = ${scaleX};
obj.scale.y = ${scaleY};
obj.scale.z = ${scaleZ};
`;
        break;
        
      case 'color':
        const { color = '#ffffff' } = params;
        codeSnippet = `
// Change object color
const obj = spline.findObjectById('${objectId}');
if (obj.material) {
  obj.material.color.set('${color}');
}

// For more complex color operations
// You can also change emissive color
if (obj.material && obj.material.emissive) {
  obj.material.emissive.set('#000000');
  obj.material.emissiveIntensity = 0.5;
}

// Or use RGB values
// obj.material.color.setRGB(1, 0, 0); // Red
`;
        break;
        
      case 'visibility':
        const { visible = true } = params;
        codeSnippet = `
// Change object visibility
const obj = spline.findObjectById('${objectId}');
obj.visible = ${visible};

// To fade out an object gradually
function fadeOut(obj, duration = 1000) {
  const startOpacity = 1;
  const endOpacity = 0;
  let startTime = null;
  
  // Store the original material
  const originalMaterial = obj.material.clone();
  
  // Make sure the material is set to be transparent
  obj.material.transparent = true;
  
  function animate(timestamp) {
    if (!startTime) startTime = timestamp;
    const elapsed = timestamp - startTime;
    const progress = Math.min(elapsed / duration, 1);
    
    obj.material.opacity = startOpacity + (endOpacity - startOpacity) * progress;
    
    if (progress < 1) {
      requestAnimationFrame(animate);
    } else {
      obj.visible = false;
      // Restore original opacity to the material
      obj.material.opacity = startOpacity;
    }
  }
  
  requestAnimationFrame(animate);
}

// To fade in an object gradually
function fadeIn(obj, duration = 1000) {
  const startOpacity = 0;
  const endOpacity = 1;
  let startTime = null;
  
  // Make sure the material is set to be transparent and object is visible
  obj.material.transparent = true;
  obj.material.opacity = startOpacity;
  obj.visible = true;
  
  function animate(timestamp) {
    if (!startTime) startTime = timestamp;
    const elapsed = timestamp - startTime;
    const progress = Math.min(elapsed / duration, 1);
    
    obj.material.opacity = startOpacity + (endOpacity - startOpacity) * progress;
    
    if (progress < 1) {
      requestAnimationFrame(animate);
    } else {
      // If material wasn't originally transparent, we could reset here
      // obj.material.transparent = false;
    }
  }
  
  requestAnimationFrame(animate);
}

// Uncomment to use fading
// ${visible ? 'fadeIn(obj, 1000);' : 'fadeOut(obj, 1000);'}
`;
        break;
        
      case 'emitEvent':
        const { eventName = 'mouseDown' } = params;
        codeSnippet = `
// Emit event on object
const obj = spline.findObjectById('${objectId}');
obj.emitEvent('${eventName}');

// Listen for events on this object
spline.addEventListener('${eventName}', (e) => {
  if (e.target.id === '${objectId}') {
    console.log('Event ${eventName} triggered on object');
    // Handle the event
  }
});

// Available events:
// - mouseDown
// - mouseUp
// - mouseHover (mouseOver)
// - mouseOut
// - keyDown
// - keyUp
// - collision
`;
        break;

      case 'material':
        const { materialId = '', materialParams = {} } = params;
        codeSnippet = `
// Change object material
const obj = spline.findObjectById('${objectId}');

// Option 1: Apply an existing material by finding it
const material = spline.findMaterialById('${materialId}');
if (material) {
  obj.material = material;
}

// Option 2: Create a new material
// Note: This is a simplified example - Spline materials are more complex
const newMaterial = new THREE.MeshStandardMaterial({
  color: ${materialParams.color ? `'${materialParams.color}'` : "'#ffffff'"},
  roughness: ${materialParams.roughness || 0.5},
  metalness: ${materialParams.metalness || 0},
  transparent: ${materialParams.transparent || false},
  opacity: ${materialParams.opacity || 1}
});

// To apply the new material:
// obj.material = newMaterial;
`;
        break;

      case 'animation':
        const { 
          animationType = 'rotate',
          duration = 1000,
          easing = 'easeInOut',
          loop = false
        } = params;
        
        let animationCode = '';
        
        if (animationType === 'rotate') {
          animationCode = `
  // Rotate animation
  const startRotation = { ...obj.rotation };
  const targetRotation = { 
    x: startRotation.x + Math.PI * 2,  // Full 360° rotation
    y: startRotation.y,
    z: startRotation.z
  };
  
  obj.rotation.x = startRotation.x + (targetRotation.x - startRotation.x) * progress;`;
        } else if (animationType === 'move') {
          animationCode = `
  // Move animation
  const startPosition = { ...obj.position };
  const targetPosition = { 
    x: startPosition.x,
    y: startPosition.y + 1,  // Move up by 1 unit
    z: startPosition.z
  };
  
  obj.position.x = startPosition.x + (targetPosition.x - startPosition.x) * progress;
  obj.position.y = startPosition.y + (targetPosition.y - startPosition.y) * progress;
  obj.position.z = startPosition.z + (targetPosition.z - startPosition.z) * progress;`;
        } else if (animationType === 'scale') {
          animationCode = `
  // Scale animation
  const startScale = { ...obj.scale };
  const targetScale = { 
    x: startScale.x * 1.5,  // Scale up by 50%
    y: startScale.y * 1.5,
    z: startScale.z * 1.5
  };
  
  obj.scale.x = startScale.x + (targetScale.x - startScale.x) * progress;
  obj.scale.y = startScale.y + (targetScale.y - startScale.y) * progress;
  obj.scale.z = startScale.z + (targetScale.z - startScale.z) * progress;`;
        }
        
        let easingFunction = '';
        
        if (easing === 'linear') {
          easingFunction = 'const ease = progress;';
        } else if (easing === 'easeIn') {
          easingFunction = 'const ease = progress * progress;';
        } else if (easing === 'easeOut') {
          easingFunction = 'const ease = 1 - Math.pow(1 - progress, 2);';
        } else { // easeInOut
          easingFunction = 'const ease = progress < 0.5 ? 2 * progress * progress : 1 - Math.pow(-2 * progress + 2, 2) / 2;';
        }
        
        codeSnippet = `
// Animate object
const obj = spline.findObjectById('${objectId}');
let startTime = null;
const duration = ${duration}; // milliseconds
let animationFrame;

function animate(timestamp) {
  if (!startTime) startTime = timestamp;
  const elapsed = timestamp - startTime;
  let progress = Math.min(elapsed / duration, 1);
  
  // Apply easing
  ${easingFunction}
  progress = ease;
  
${animationCode}
  
  if (progress < 1) {
    animationFrame = requestAnimationFrame(animate);
  } else if (${loop}) {
    // Reset for looping
    startTime = null;
    animationFrame = requestAnimationFrame(animate);
  }
}

// Start animation
animationFrame = requestAnimationFrame(animate);

// To stop animation early:
// cancelAnimationFrame(animationFrame);
`;
        break;
        
      default:
        throw new Error(`Unsupported action: ${action}`);
    }
    
    return `
import { Application } from '@splinetool/runtime';

// Create a new Application instance
const canvas = document.getElementById('canvas3d');
const spline = new Application(canvas);

// Load the scene
spline.load('${sceneUrl}').then(() => {
  console.log('Scene loaded successfully');
  
  ${codeSnippet}
});
`;
  }

Tool Definition Quality

D1/5.0
Behavior1/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Tool has no description.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness1/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Tool has no description.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness1/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Tool has no description.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters1/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Tool has no description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose1/5

Does the description clearly state what the tool does and how it differs from similar tools?

Tool has no description.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines1/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Tool has no description.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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