// In tessellation control shaders
out float gl_TessLevelOuter ;
// In tessellation evaluation shaders
Available only in the tessellation control and evaluation languages, gl_TessLevelOuter is used to assign values to the corresponding outer tesellation levels of the current patch. The values written into gl_TessLevelOuter by the tessellation control shader are used by the tessellation primitive generator to control primitive tessellation and may be read by the subsequent tessellation evaluation shader.
As inputs to the tessellation evaluation shader, gl_TessLevelOuter contains the values written by the tessellation control shader, if present. If no tessellation control shader is present, it contains the default tessellation level.
OpenGL Shading Language Version
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