Difference between revisions of "Default Shader"
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Revision as of 22:34, 17 December 2020
Node Description and Purpose:
The Default Shader is a versatile node that can provide base color or load external images, as well as allowing control of translucency, luminosity, specular effects, displacement, and opacity. The Default Shader forms the basis for object surface mapping.
Many aspects of this node are made up of a group of related parameters. For example the diffuse colour aspect has parameters for a colour (Diffuse colour), an image file (Colour image) and a function (Color function). All of these parameters work together to control the particular aspect they relate to, in this case the diffuse colour.
This has implications you might not expect. For example lets say you want to use an image for the diffuse colour, perhaps mapping an image of a leaf on the leaf polygons of a plant model. For the true colours of the image to come through you need to set the Diffuse colour to white. If it was set to some other colour that colour would influence the colours from the image. Let's say you set the Diffuse colour to red. This would give the colours from the image a red tint. You can use this to your advantage. If you thought the image was too bright you could use a grey colour to make it darker.
Generally speaking though you do need to keep in mind that the different parameters of each aspect interact with each other. This makes the shader versatile but until you understand how it works you might find it pays to make changes step by step and render previews to see what effect they're having rather than just jumping in and making many changes at once.
Here's some tips that apply pretty generally to the different aspects of the shader:
To specify a basic colour:
- Choose a colour with the colour param
- Don't specify anything for the image and function params.
To use an image and get the colours directly from the image:
- Choose a file with the image param.
- Set the colour param to white.
- Don't specify anything for the function param.
To use the colours directly from a shader or function:
- Attach a shader or function using the function param.
- Set the colour param to white.
- Don't specify anything for the image param.
To use an image or function to control where the colour appears:
- Specify the colour using the colour param.
- Specify a greyscale image or function. More of the specified colour will appear where the image or function is lighter. White means full colour, black means no colour (which is the same as black).
Node Type: Other Surface Shader
- Diffuse colour: This specifies the basic colour of the shader.
Colour image: Allows to you choose an image file to use for the diffuse colour.
Colour function: This lets you specify a function or shader to generate the diffuse colour.
Translucency: Translucency gives an effect of light filtering through a surface. For example you might use translucency on a leaf texture to simulate light passing through it. It's not the same thing as opacity. Translucency is explained in more detail here.
Translucency image: Allows you to choose an image file to control translucency.
Translucency function: This lets you specify a function or shader to control translucency.
Luminosity: Luminosity gives the effect of a glow. See the Surface Layer - Luminosity Tab page for a more detailed discussion about using the luminosity parameters.
Luminosity image: Allows you to choose an image file for the luminosity.
Luminosity function : This lets you specify a function or shader to generate the luminosity.
Additional tabs for Default Shader
Literally, to change the position of something. In graphics terminology to displace a surface is to modify its geometric (3D) structure using reference data of some kind. For example, a grayscale image might be taken as input, with black areas indicating no displacement of the surface, and white indicating maximum displacement. In Terragen 2 displacement is used to create all terrain by taking heightfield or procedural data as input and using it to displace the normally flat sphere of the planet.
A shader is a program or set of instructions used in 3D computer graphics to determine the final surface properties of an object or image. This can include arbitrarily complex descriptions of light absorption and diffusion, texture mapping, reflection and refraction, shadowing, surface displacement and post-processing effects. In Terragen 2 shaders are used to construct and modify almost every element of a scene.