The Lego Project CG Workshop

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The Lego ProjectCG Workshop

• the lego modeling project
• summer 2005

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The Goal

• Create an interactive Lego modeling application.
• In the application we will be able to
• Create Lego bricks.
• Create Lego models.
• Color and texture them.
• Save them as 3D meshes.
• And anything else you can think of!!!

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Examples
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Examples
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How do you do that?

• Use graphics APIs (OpenGL or DirectX) for
  rendering and modeling.
• The user will have
• Modeling Controls
• Camera Controls
• Lights
• Textures
• ...
• Use whichever GUI you want.

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• Modeling using Lego bricks.
• Creating different Lego bricks.

• Textures and colors.
• Exporting 3D models.

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Introduction

• Interactive modeling
• UI Design.
• Mouse and keyboard controls.
• Real time rendering
• Render using graphic library
• Visual quality lights, textures, materials
• Interactive frame rates (fast)

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Requirements

• No A.I.
• Friendly UI
• Mouse control the user drags objects with the
  mouse to valid locations
• Camera control the camera can navigate to view
  the model from different directions.

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Modeling
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Brick Creation

• Define height and width values for a brick and
  use them to define the bricks.
• Define bottom and top attach points.
• Define additional brick planes (e.g. roof bricks).

1h x 3w x 2w
Roof bricks have additional planes
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Lego Modeling

• Bricks are attached to each other and become
  objects that can be placed and attached.
• objects can be dismantled into smaller objects
  and bricks.

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Lego Modeling

• Lego bricks are placed in the world using
  translations and 90o rotations in Tetris Mode.

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Modeling Applications

• Classical modeling applications usually have
  multiple views (top, front, perspective...).

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Coloring and Texturing
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Coloring and Texturing

• Assign each brick a color (material).
• Give the user the ability to apply texture
  mapping to the model.

Cheating is allowed up to a point ... ask me when
you get to this part.
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Coloring and Texturing

• Drawing directly on the objects. A simple paint
  brush like application. The drawing will be onto
  a texture that will be applied to the object.

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3D model exporting
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3D models

• Save the outer (visible) part of the model as a
  3D mesh in one of the standard file formats (obj
  file format).
• These models
• can be used with
• any standard
• 3D application.

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Administrative Stuff
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Administrative Stuff

• Next week each group will present its initial
  approach to problem.
• After 4-5 weeks (beginning of August), the groups
  will present their initial implementation and
  progress report.
• At the end of the semester each group will
  present their application.

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Administrative Stuff

• Each group can be of 2-3 students. Groups of 3
  have to make a more impressive project (add more
  features, nicer user interface...)
• Part of the grade will depend on the performance
  of the application (interactivity and usability)
  which will be relative to the other groups.

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How to Approach the Project

• Build the scene
• Basic rendering.
• Lights.
• Camera controls.
• ...
• Lego modeling
• Brick data structure.
• Controls.
• Snapping.
• ...

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How to Approach the Project

• Lego Modeling Continued
• Taking objects apart.
• Attaching objects
• ...
• Brick Editing
• Create new bricks.
• Export them to the modeller.
• ...

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How to Approach the Project

• Extract the 3D Model.
• Texturing and Modeling
• Add texture mapping.
• Create a simple drawing interface.
• Add the drawing as textures.
• ...