180 lines
6.1 KiB
ReStructuredText
180 lines
6.1 KiB
ReStructuredText
.. _doc_fixed_materials:
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Fixed Materials
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===============
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Introduction
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------------
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Fixed materials (originally Fixed Pipeline Materials) are the most
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common type of materials, using the most common material options found
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in 3D DCCs (such as Maya, 3DS Max or Blender). The big advantage of
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using them is that 3D artists are very familiar with this layout. They
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also allow to try out different things quickly without the need of
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writing shaders. Fixed Materials inherit from
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:ref:`Material <class_Material>`,
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which also has several options. If you haven't read it before, reading
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the :ref:`doc_materials` tutorial is recommended.
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Options
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-------
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Here is the list of all the options available for fixed materials:
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.. image:: /img/fixed_materials.png
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From this point, every option will be explained in detail:
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Fixed Flags
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-----------
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These are a set of flags that control general aspects of the material.
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Use Alpha
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~~~~~~~~~
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This flag needs to be active for transparent materials to blend with
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what is behind, otherwise display will always be opaque. Do not enable
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this flag unless the material really needs it, because it can severely
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affect performance and quality. Materials with transparency will also
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not cast shadows (unless they contain opaque areas and the "opaque
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pre-pass" hint is turned on, see the :ref:`doc_materials` tutorial for more
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information).
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.. image:: /img/fixed_material_alpha.png
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Use Vertex Colors
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~~~~~~~~~~~~~~~~~
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Vertex color painting is a very common technique to add detail to
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geometry. 3D DCCs all support this, and many even support baking
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occlusion to it. Godot allows this information to be used in the fixed
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material by modulating the diffuse color when enabled.
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.. image:: /img/fixed_material_vcols.png
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Point Size
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~~~~~~~~~~
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Point size is used to set the point size (in pixels) for when rendering
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points. This feature is mostly used in tools and HUDs
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Discard Alpha
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~~~~~~~~~~~~~
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When alpha is enabled (see above) the invisible pixels are blended
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with what is behind them. In some combinations (of using alpha to
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render depth) it may be possible that invisible pixels cover other
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objects.
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If this is the case, enable this option for the material. This option
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is often used in combination with "opaque pre-pass" hint (see the
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:ref:`doc_materials` tutorial for more information).
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Parameters
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----------
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Diffuse, Specular, Emission and Specular Exponent
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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These are the base colors for the material.
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- Diffuse Color is responsible for the light that reaches the material,
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then gets diffused around. This color varies by the angle to the
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light and the distance (in the case of spot and omni lights). It is
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the color that best represents the material. It can also have alpha
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(transparency)
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- Specular color is the color of the reflected light and responsible
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for shines. It is affected by the specular exponent.
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- Emission is the color of the light generated within the material
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(althought it will not lit anything else around unless baking). This
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color is constant.
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- Specular Exponent (or "Shininess"/"Intensity" in some 3D DCCs) is the
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way light is reflected. If the value is high, light is reflected
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completely, otherwise it is diffused more and more.
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Below is an example of how they interact:
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.. image:: /img/fixed_material_colors.png
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Shader & Shader Param
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~~~~~~~~~~~~~~~~~~~~~
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Regular shader materials allow custom lighting code. Fixed materials
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come with four predefined shader types:
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- **Lambert**: The standard diffuse light, where the amount of light is
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proportional to the angle with the light emissor.
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- **Wrap**: A variation on Lambert, where the "coverage" of the light
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can be changed. This is useful for many types of materials such as
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wood, clay, hair, etc.
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- **Velvet**: This is similar to Lambert, but adds light scattering in
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the edges. It's useful for leathers and some types of metals.
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- **Toon**: Standard toon shading with a coverage parameter. The
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specular component also becomes toon-ized.
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.. image:: /img/fixed_material_shader.png
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Detail & Detail Mix
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~~~~~~~~~~~~~~~~~~~
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Detail is a second diffuse texture which can be mixed with the first one
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(more on textures later!). Detail blend and mix control how these are
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added together, here's an example of what detail textures are for:
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.. image:: /img/fixed_material_detail.png
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Normal Depth
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~~~~~~~~~~~~
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Normal depth controls the inensity of the normal-mapping as well as the
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direction. On 1 (the default) normalmapping applies normaly, on -1 the
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map is inverted and on 0 is disabled. Intermediate or greater values are
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accepted. Here's how it's supposed to look:
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.. image:: /img/fixed_material_normal_depth.png
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Glow
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~~~~
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This value controls how much of the color is sent to the glow buffer. It
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can be greater than 1 for a stronger effect. For glow to work, a
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WorldEnvironment must exist with Glow activated.
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.. image:: /img/fixed_material_glow.png
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Blend Mode
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~~~~~~~~~~
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Objects are usually blended in Mix mode. Other blend modes (Add and Sub)
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exist for special cases (usually particle effects, light rays, etc) but
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materials can be set to them:
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.. image:: /img/fixed_material_blend.png
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Point Size, Line Width
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~~~~~~~~~~~~~~~~~~~~~~
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When drawing points or lines, the size of them can be adjusted here per
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material.
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Textures
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--------
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Almost all of the parameters above can have a texture assigned to them.
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There are four options to where they can get their UV coordinates:
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- **UV Coordinates (UV Array)**: This is the regular UV coordinate
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array that was imported with the model.
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- **UV x UV XForm**: UV Coordinates multiplied by the UV Xform matrix.
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- **UV2 Coordinates**: Some imported models might have come with a
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second set of UV coordinates. These are common for detail textures or
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for baked light textures.
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- **Sphere**: Spherical coordinates (difference of the normal at the
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pixel by the camera normal).
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The value of every pixel of the texture is multiplied by the original
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parameter. This means that if a texture is loaded for diffuse, it will
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be multiplied by the color of the diffuse color parameter. Same applies
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to all the others except for specular exponent, which is replaced.
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