原文地址:Docs » Shading » Shading reference » CanvasItem shaders
内置光属性(Light built-ins)
相对于3D着色器，2D着色器光函数的工作方式有所不同。在2D着色器中，光函数会在物体被绘制的时候调用一次，然后对场景中每一个触及到这个物体的光都调用一次。如果你不希望任何光影响到某一个物体可以使用unshaded渲染模式。如果你只希望一个物体被光覆盖的地方可见，那么可以使用light_only渲染模式。
当一个着色器(所属的物体)处于光照中时，内置光属性AT_LIGHT_PASS的值将为true
| 内置光属性 | 描述 |
|---|---|
| in vec4 FRAGCOORD | Fragment coordinate of pixel center. Origin at lower left. |
| in vec3 NORMAL | Input Normal. Although this value is passed in, normal calculation still happens outside of this function. |
| in vec2 UV | UV from vertex function, equivalent to the UV in the fragment function. |
| in vec4 COLOR | Input Color. This is the output of the fragment function with final modulation applied. |
| sampler2D TEXTURE | Current texture in use for CanvasItem. |
| in vec2 TEXTURE_PIXEL_SIZE | Normalized pixel size of default 2D texture. For a Sprite with a texture of size 64x32px, TEXTURE_PIXEL_SIZE = vec2(1/64, 1/32)
|
| in vec2 SCREEN_UV | SCREEN_TEXTURE Coordinate (for using with screen texture). |
| in vec2 POINT_COORD | UV for Point Sprite. |
| in float TIME | Global time in seconds. |
| inout vec2 LIGHT_VEC | Vector from light to fragment, can be modified to alter shadow computation. |
| inout float LIGHT_HEIGHT | Height of Light. Only effective when normals are used. |
| inout vec4 LIGHT_COLOR | Color of Light. |
| in vec2 LIGHT_UV | UV for Light texture. |
| out vec4 SHADOW_COLOR | Shadow Color of Light. |
| inout vec4 LIGHT | Value from the Light texture and output color. Can be modified. If not used, the light function is ignored. |
