Depth, blending & cullingGL 4.0

glMinSampleShading

Under MSAA, makes the fragment shader run for a share of the samples (1.0 = every sample), smoothing aliasing inside triangles too.

Signature

void glMinSampleShading(GLfloat value);

How it works

Plain MSAA runs the fragment shader once per pixel and copies the result to every covered sample, so only triangle edges get smoother. Aliasing that comes from the shader itself (thin specular highlights, alpha-tested foliage, sharp procedural patterns) stays.

With glEnable(GL_SAMPLE_SHADING) and glMinSampleShading(1.0), the shader runs once per sample: in effect supersampling, with the matching cost (4× MSAA means up to 4× the fragment work). Values between 0 and 1 ask for at least that fraction of the samples.

Parameters

valueGLfloat

Fraction of samples to shade, 0 to 1 (clamped).

Tips & pitfalls

  • It does nothing unless GL_SAMPLE_SHADING is enabled and the framebuffer is multisampled.

  • A shader that reads gl_SampleID or uses the sample qualifier is run per sample automatically.

Example

example.cpp
1glEnable(GL_MULTISAMPLE);
2glEnable(GL_SAMPLE_SHADING);
3glMinSampleShading(1.0);   // shade every sample

Related

glRenderbufferStorageMultisampleAllocates a renderbuffer with several samples per pixel, for MSAA in your own framebuffer.glEnableSwitches on a fixed-function feature such as depth testing, blending or face culling.glBlitFramebufferCopies a rectangle of pixels from the read framebuffer to the draw framebuffer, scaling and resolving MSAA on the way.
Official Khronos documentation