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

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SE 313 – Computer Graphics

Lecture 13: Lighting and Materials Practice

Lecturer: Gazihan Alankuş

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Today• Lights and materials• Normal mapping

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Lights• We learned that the color of the light and the

material are used to determine rendering colors

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

material to it.

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Lights• Render the scene.

• This is what you should see.

• Press Esc to go back

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Lights• Select the lamp

• Go to the Object Data tab

• Change the color of the lamp to bright red

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

will appear red

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Lights• Now let’s change the material to blue• Select the cube and go to the material tab

• Change the diffuse color tobright blue

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

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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 between

diffuse and specular– Change the diffuse color to green– Change the specular color to red

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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

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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

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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 sphere

will ignore the environment light and will have dark sides as before

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Light: Ambient• Increase it a bit and see how it

affects rendering.

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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

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Today• Lights and materials• Normal mapping

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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

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

Icosphere by about 1.3.

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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)

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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.

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

texture

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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.

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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

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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

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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.

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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

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Normal Mapping: Using the Normal Texture• Select the cube and add a material and a

texture to it

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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 Color

and check Normal

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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

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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

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Normal Mapping: Final Preparations• Reset the 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

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Normal Mapping: Using it in Unity• Run Unity and create a new project in your

hard drive• In My Computer, find the folder

that you put the files, and dragit into the Project pane of Unity

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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

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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

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Normal Mapping: Using it in Unity• Change the Shader to Bumped

Diffuse. • Now we have two texture slots,

one for the regular texture and onefor the normal map.

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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

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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 like

how it was in Blender• Add a directional light to see it

better

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

a sphere

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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

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Normal Mapping: Using it in Unity• Select the Directional Light

• Rotate it

• See how the cube reflects this lightEven though it is flat!

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Lab• Now, map the normal vectors of a cube onto a

sphere– Demonstrate it both in Blender and in Unity