Texture:setDepthSampleMode
Sets the comparison mode used when sampling from a depth texture in a shader. Depth texture comparison modes are advanced low-level functionality typically used with shadow mapping in 3D.

When using a depth texture with a comparison mode set in a shader, it must be declared as a sampler2DShadow and used in a GLSL 3 Shader. The result of accessing the texture in the shader will return a float between 0 and 1, proportional to the number of samples (up to 4 samples will be used if bilinear filtering is enabled) that passed the test set by the comparison operation.

Depth texture comparison can only be used with readable depth-formatted Canvases.
Texture:setDepthSampleMode( compare )
compare CompareMode The comparison mode used when sampling from this texture in a shader.