放射光源Emissive lighting

放射光源是物件發出的光線,例如光芒。Emissive lighting is light that is emitted by an object; for example, a glow. 放射呈現物件看起來像自體發光。Emission makes a rendered object appear to be self-luminous. 放射會影響物件的色彩,例如讓深色材質更亮,並呈現部分的發出色彩。Emission affects an object's color and can, for example, make a dark material brighter and take on part of the emitted color.

放射光源是以單一字詞描述。Emissive lighting is described by a single term.

放射光源 = CₑEmissive Lighting = Cₑ

其中:where:

參數Parameter 預設值Default value 類型Type 描述Description
CₑCₑ (0,0,0,0)(0,0,0,0) 紅色、綠色、藍色以及 alpha 透明度 (全都是浮點值)Red, green, blue, and alpha transparency (all floating-point values) 放射色彩。Emissive color.

 

Cₑ 的值為色彩 1 或色彩 2。The value for Cₑ is either color 1 or color 2. 如果未提供頂點色彩,則會使用材質放射色彩。If the vertex color is not provided, the material emissive color is used.

範例Example

在此範例中,物件使用場景環境光線和材料環境色彩上色。In this example, the object is colored using the scene ambient light and a material ambient color.

根據公式,產生的物件頂點色彩為材質色彩。According to the equation, the resulting color for the object vertices is the material color.

下圖顯示材質色彩,也就是綠色。The following illustration shows the material color, which is green. 放射光線使用相同色彩照亮所有物件端點。Emissive light lights all object vertices with the same color. 其不取決於頂點標準或光線方向。It is not dependent on the vertex normal or the light direction. 如此一來,球體看起來像是 2D 圓形,因為物件表面周圍的陰影並無差別。As a result, the sphere looks like a 2D circle because there is no difference in shading around the surface of the object.

綠色球體圖例

下圖顯示放射光線如何與其他三種光線混合。The following illustration shows how the emissive light blends with the other three types of lights. 在球體右側,有綠色放射光線和紅色環境光線的混合。On the right side of the sphere, there is a blend of the green emissive and the red ambient light. 在球體左側,綠色放射光線與紅色環境和擴散光線混合,產生紅色漸層。On the left side of the sphere, the green emissive light blends with red ambient and diffuse light producing a red gradient. 反射強光中心為白色,在反射光線值驟然消失時會產生黃色光環,使得環境、擴散和放射光線值彼此混合而產生黃色。The specular highlight is white in the center and creates a yellow ring as the specular light value falls off sharply leaving the ambient, diffuse and emissive light values which blend together to make yellow.

有放射光線的綠色球體圖

相關主題Related topics

光源的數學運算Mathematics of lighting