Transparent Bumped Diffuse
Reference Manual > Built-in Shader Guide > Transparent Shader Family > Transparent Bumped Diffuse

Transparent Bumped Diffuse

Transparent Properties

This shader can make mesh geometry partially or fully transparent by reading the alpha channel of the main texture. In the alpha, 0 (black) is completely transparent while 255 (white) is completely opaque. If your main texture does not have an alpha channel, the object will appear completely opaque.

Using transparent objects in your game can be tricky, as there are traditional graphical programming problems that can present sorting issues in your game. For example, if you see odd results when looking through two windows at once, you're experiencing the classical problem with using transparency. The general rule is to be aware that there are some cases in which one transparent object may be drawn in front of another in an unusual way, especially if the objects are intersecting, enclose each other or are of very different sizes. For this reason, you should use transparent objects if you need them, and try not to let them become excessive. You should also make your designer(s) aware that such sorting problems can occur, and have them prepare to change some design to work around these issues.

Bumped Properties

This shader is a Pixel-Lit shader, which is more expensive than Vertex-Lit. Pixel lighting is expensive mostly because each object has to be drawn multiple times for each pixel light that shines on it. Vertex lights don't affect the shader in this way. Pixel lights support cookies, bumpmapping, and shadows while vertex lights do not. Pixel lights are also much less sensitive to tesselation of the models - if you have a cube using this shader, you can put point light very close to its surface and it will have nice round highlight. This effect cannot be achieved with Vertex lighting.

Like a Diffuse shader, this computes a simple (Lambertian) lighting model. The lighting on the surface decreases as the angle between it and the light decreases. The lighting depends only on the this angle, and does not change as the camera moves or rotates around.

Bumpmapping simulates small surface details using a texture, instead of spending more polygons to actually carve out details. It does not actually change the shape of the object, but uses a special texture called a Bumpmap (also called a Normal Map) to achieve this effect. In the Bumpmap, each pixel's color value represents the angle of the surface normal. Then by using this value instead of the one from geometry, lighting is computed. The Bumpmap effectively overrides the mesh's geometry when performing lighting of the object.

Creating Bumpmaps

You can import a regular grayscale image and convert it to a Normal Map from within Unity. To learn how to do this, please read the Bumpmap FAQ page.

Technical Details

The Normal Map is a tangent space type of Normal Map. Tangent space is the space that "follows the surface" of the model geometry. In this space, Z always points away from the surface. Tangent space Normal Maps are a bit more expensive than the other "object space" type Normal Maps, but have some advantages:

  1. It's possible to use them on deforming models - the bumps will remain on the deforming surface and will just work.
  2. It's possible to reuse parts of the Bumpmap on different areas of a model; or use them on different models.

Diffuse Properties

This shader is a Pixel-Lit shader, which is more expensive than Vertex-Lit. Pixel lighting is expensive mostly because each object has to be drawn multiple times for each pixel light that shines on it. Vertex lights don't affect the shader in this way. Pixel lights support cookies, bumpmapping, and shadows while vertex lights do not. Pixel lights are also much less sensitive to tesselation of the models - if you have a cube using this shader, you can put point light very close to its surface and it will have nice round highlight. This effect cannot be achieved with Vertex lighting.

Diffuse computes a simple (Lambertian) lighting model. The lighting on the surface decreases as the angle between it and the light decreases. The lighting depends only on the this angle, and does not change as the camera moves or rotates around.

Performance

Generally, this shader is cheap to render. For more details, please view the Shader Peformance page.