Eyeon:Manual/Fusion 6/Phong
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The Phong tool is a basic illumination material which can be applied to geometry in the 3D scene. It describes how the object will respond to light, and provides a large number of texture map inputs to allow fine control over the diffuse, specular and bumpmap components of the material.
While producing a highlight similar to that produced by the Blinn model, it is more commonly used for shiny/polished plastic surfaces. A more technical description of the Phong shader can be found at http://en.wikipedia.org/wiki/Phong_shading
External Inputs
- Phong.DiffuseTex
- [ orange, optional ] This input will accept a 2D image or a 3D material to be used as a diffuse texture map.
- Phong.SpecularColorTex
- [ green, optional ] This input will accept a 2D image or a 3D material to be used as a specular color texture map.
- Phong.SpecularIntensityTex
- [ magenta, optional ] This input will accept a 2D image or a 3D material to be used as an intensity map for the materials specular highlights. When the input is a 2D image the alpha channel is used to create the map while the color channels are discarded.
- Phong.SpecularExponentTex
- [ light blue, optional ] This input will accept a 2D image or a 3D material to be used as an falloff map for the materials specular highlights. When the input is a 2D image the alpha channel is used to create the map while the color channels are discarded.
- Phong.BumpmapTex
- [ white, optional ] This input will accept a 2D image or a 3D material then uses the RGB information as texture-space normals.
Each of these inputs multiplies the pixels in the texture map by the equivalently named parameters in the tool itself. This provides an effective method for "scaling" parts of the material.
Controls
Diffuse
Diffuse describes the base surface characteristics without any additional effects like reflections or specular highlights. In addition to defining the base color of an object, the diffuse color also defines the transparency of the object. The alpha in a diffuse texture map can be used to make portions of the surface of any object the material is applied to transparent.
A materials diffuse color describes the base color presented by the material when it is lit indirectly or by ambient light. If a diffuse texture map is provided then the color value provided here is multiplied by the color values in the texture.
This slider sets the material's Alpha channel value. This affects diffuse and specular colors equally, and affects the alpha value of the material in the rendered output. If a diffuse texture map is provided then the alpha value set here is multiplied by the alpha values in the texture map.
Reducing the material's Opacity will decrease the color and alpha values of the specular and diffuse colors equally, making the material transparent.
Specular
The parameters in the Specular section describes the look of the specular highlight of the surface. These values are evaluated in a different way for each illumination model. See the Notes for more details.
Specular Color determines the color of light that reflects from a shiny surface. The more specular a material is, the glossier it appears. Surfaces like plastics and glass tend to have white specular highlights, whereas metallic surfaces like gold have specular highlights that inherit their color from the material color. If a specular texture map is provided then the value provided here is multiplied by the color values from the texture.
Specular Intensity controls how strong the specular highlight is. If the specular intensity texture is provided then this value is multiplied by the alpha value of the texture.
Specular Exponent controls the falloff of the specular highlight. The greater the value, the sharper the falloff, and the smoother and glossier the material appears. If the specular exponent texture is provided then this value is multiplied by the alpha value of the texture map.
Transmittance
Transmittance controls the way light passes through a material. For example, a solid blue sphere will cast a black shadow, but one made of translucent blue plastic would cast a much lower density blue shadow.
There is a separate opacity option. Opacity determines how transparent the actual surface is when it is rendered. Fusion allows for adjusting both opacity and transmittance separately. This might be a bit counter-intuitive to artists who are unfamiliar with 3D software at first. It is possible to have a surface that is fully opaque but transmits 100% of the light arriving upon it, effectively making it a a luminous / emissive surface.
- Attenuation determines how much color is passed through the object. For an object to have transmissive shadows, set the attenuation to (1, 1, 1), which means 100% of green, blue, red light pass through the object. Setting this color to RGB (1, 0, 0) means that the material will transmit 100% of the red arriving at the surface but none of the green or blue light. This allows for 'stained glass' shadows.
- When the Alpha Detail slider is set to 0, the alpha channel of the object is ignored and the entire object casts a shadow. If it is set to 1, the alpha channel detemines what portions of the object cast a shadow.
- The Color Detail slider modulates light passing through the surface by the diffuse color + texture colors. Use this to throw a shadow that contains color details of the texture applied to the object. Increasing the slider from 0 to 1 brings in more of diffuse color + texture color into the shadow. Note that the alpha and opacity of the object is ignored when transmitting color, allowing an object with a solid alpha to still transmit its color to the shadow.
- The Saturation slider controls the saturation of the color component transmitted to the shadow. Setting this to 0.0 will result in monochrome shadows.
These checkboxes control whether the material is affected by lighting and shadows in the scene. If turned off, the object will always be fully lit and/or unshadowed.
This makes the surface effectively two-sided by adding a second set of normals facing the opposite direction on the back side of the surface. This is normally off, to increase rendering speed, but can be turned on for 2D surfaces or for objects that are not fully enclosed, to allow the reverse or interior surfaces to be visible as well.
Normally, in a 3D application only the front face of a surface is visible and the back face is culled, so that if a camera were to revolve around a plane in a 3D application when it reached the backside, the plane would become invisible. Making a plane two sided in a 3D application is equivalent to adding another plane on top of the first but rotated by 180 degrees so the normals are facing the opposite direction on the backside. Thus, when you revolve around the back, you see the second image plane which has its normals facing the opposite way.
Fusion does exactly the same thing as 3D applications when you make a surface two sided. The confusion about what two-sided does arises because Fusion does not cull backfacing polygons by default. If you revolve around a one-sided plane in Fusion you will still see it from the backside (but you are seeing the frontside bits duplicated through to the backside as if it were transparent). Making the plane two sided effectively adds a second set of normals to the backside of the plane.
Note this can become rather confusing once you make the surface transparent, as the same rules still apply and produce a result which is counter-intuitive. If you view from the frontside a transparent two-sided surface illuminated from the backside, it will look unlit.
This slider sets the numeric identifier assigned to this material. This value will be rendered into the MatID auxiliary channel if the according option is enabled in the renderer.
Tips for Phong (edit)
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