SE 313 – Computer Graphics

1. SE 313 – Computer Graphics Lecture 13: Lighting and Materials Practice Lecturer: GazihanAlankuş

2. Today • Lights and materials • Normal mapping

3. Lights • We learned that the color of the light and the material are used to determine rendering colors

4. Lights • Create a new default Blender scene • The cube should have a material. If not, add a material to it.

5. Lights • Render the scene. • This is what you should see. • Press Esc to go back

6. Lights • Select the lamp • Go to the Object Data tab • Change the color of the lamp to bright red

7. Lights • Render it. Even though the object is not red, it will appear red

8. Lights • Now let’s change the material to blue • Select the cube and go to the material tab • Change the diffuse color tobright blue

9. Lights • Render it • Did you expect purple? Why did this happen?

10. Light: Diffuse and Specular • Now create a new scene, delete the cube and add a UVSphere • Add a material to it • Let’s see the difference betweendiffuse and specular • Change the diffuse color to green • Change the specular color to red

11. Light: Diffuse and Specular • Render the scene and notice the hint of red near where the light shines • Change specular back to white and render • Notice the difference

12. Light: Ambient • To enable ambient light in the scene, we need to add it to the environment • Go to the world tab • Enable Environment Lighting • Energy:1 means it’s on • Render the sphere and see that it does not have dark sides anymore

13. Light: Ambient • We can reduce the ambient light’s energy, or reduce how much the material reflects it • Select the sphere and go to the material tab • Under Shading, reduce Ambient to 0 • When you render now, the spherewill ignore the environment light and will have dark sides as before

14. Light: Ambient • Increase it a bit and see how it affects rendering.

15. Light: Emission • We can also simulate objects emitting light • In the same pane, increase Emit to 2 • Now the sphere is more uniformly lit as if it is giving out light

16. Today • Lights and materials • Normal mapping

17. Normal Mapping • We are going to map the normal vectors of one object to another • This will be stored as a texture. The red, green and blue components of the texture will actually represent x, y and z components of the normal vector • We will see how we can render this in Blender • We will see how to make this work in Unity

18. Normal Mapping • Start with a new project • Create a cube and a Icosphere. Scale up the Icosphere by about 1.3.

19. Normal Mapping: Preparing the Texture • We are going to map the normals of the sphere to the cube. This will be stored in a texture in the cube. For this, we need to prepare our cube for texture mapping. • First split the main view and bring the UV/Image Editor on the left (Right click)

20. Normal Mapping: Preparing the Texture • Select the cube in the 3D view, go to edit mode, while all faces are selected, unwrap the model using smart uv project.

21. Normal Mapping: Preparing the Texture • Create a blank image and name it normal texture

22. Normal Mapping • The sphere has normal vectors that are a natural result of its shape. • We are going to artificially put (bake) those normal vectors on the cube so that they can be used while rendering to make the cube look a bit like the sphere. • The texture on the cube will hold these normal vectors.

23. Normal Mapping: Baking the Normals • Go to object mode • It is really important that you do this selection exactly in the order it is explained below • Select the sphere first and then shift+select the cube • Think of it as of “from sphere to cube” • The cube should have a yellow outline and the sphere should have an orange outline

24. Normal Mapping: Baking the Normals • Without breaking this selection, go to the render pane • Scroll down to Bake • Select Normals as the bake mode • Check Selected to Active • Click on Bake to start baking

25. Normal Mapping: Baking the Normals • In the UV/Image editor you should see something like this • This is the encoding of x, y, z values of normal vectors into red, green, bluecomponents of the texture. • If you don’t see this, check the thumbnail • If the thumbnail is not black and looks like this, then this is a Blender bug. Save the blend file and the texture, and then reload the imageto fix this.

26. Normal Mapping: Using the Normal Texture • Now turn on the texture mode in the 3D view and move away the sphere. This is what your cube should look like

27. Normal Mapping: Using the Normal Texture • Select the cube and add a material and a texture to it

28. Normal Mapping: Using the Normal Texture • Now let’s prepare the texture. Set its type to Image or Movie • Select the image from the combo • Check Normal Map under Image Sampling • Under Mapping, set Coordinate to UV • Under Influence, uncheck Colorand check Normal

29. Normal Mapping: Viewing the Normal Mapping • Now we changed this texture to be used as a normal map. We can see this in the 3D view by changing some settings. • Make sure the Properties pane is open in the 3D view • Scroll down to Display • For Shading, select GLSL • Now your cube looks different

30. Normal Mapping: Viewing the Normal Mapping • The cube is rendered differently • Instead of its geometrically calculated normals, its using normals mapped using the texture • Turn the cube to see that it really is trying to act like a sphere

31. Normal Mapping: Final Preparations • Resetthe rotation of the cube to 0 • Delete the sphere • Create a new folder • Save the blender scene in this folder • Save the image in the same folder

32. Normal Mapping: Using it in Unity • Run Unity and create a new project in your hard drive • In My Computer, find the folderthat you put the files, and dragit into the Project pane of Unity

33. Normal Mapping: Using it in Unity • When you click on the model you should see its preview like this • Note that Unity didn’t realize that our texture was a normal map and it’s using it as a regular texture. We will fixthis

34. Normal Mapping: Using it in Unity • Drag the model into the scene • In the inspector, you will see the material on the bottom. • The material is using our texture as a regular texture. • We need another kind of material that accepts normal maps

35. Normal Mapping: Using it in Unity • Change the Shader to BumpedDiffuse. • Now we have two texture slots, one for the regular texture and onefor the normal map.

36. Normal Mapping: Using it in Unity • We need to put our texture into the normal map rather than the regular texture • Click on Select in the regular texture • Select none • Click on Select in the normal map texture • Select the correct texture

37. Normal Mapping: Using it in Unity • Click on Fix Now below to get Unity to really use this texture as a normal map • Now our cube looks more likehow it was in Blender • Add a directional light to see itbetter

38. Normal Mapping: Using it in Unity • Turn it to see that it really is reflecting light like a sphere

39. Normal Mapping: Using it in Unity • To see this in the game view, you can drag and dock it separately • If you don’t see it, you need to select Main Camera in Hierarchy pane and select GameObject->Align with View in the menu

40. Normal Mapping: Using it in Unity • Select the Directional Light • Rotate it • See how the cube reflects this lightEven though it is flat!

41. Lab • Now, map the normal vectors of a cube onto a sphere • Demonstrate it both in Blender and in Unity