在lod基础上进行采样。

gvec4 textureLod( gsampler2D sampler,
vec2 P,
float lod);

gvec4 textureLod( gsampler3D sampler,
vec3 P,
float lod);

gvec4 textureLod( gsamplerCube sampler,
vec3 P,
float lod);

float textureLod( sampler2DShadow sampler,
vec3 P,
float lod);

gvec4 textureLod( gsampler2DArray sampler,
vec3 P,
float lod);

Parameters

sampler

Specifies the sampler to which the texture from which texels will be retrieved is bound.

指定采样器
P

Specifies the texture coordinates at which texture will be sampled.

指定纹理坐标
lod

Specifies the explicit level-of-detail

指定lod