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docs/gallium/cso/dsa.rst

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+.. _depth-stencil-alpha:
+
+Depth, Stencil, & Alpha
+=======================
+
+These three states control the depth, stencil, and alpha tests, used to
+discard fragments that have passed through the fragment shader.
+
+Traditionally, these three tests have been clumped together in hardware, so
+they are all stored in one structure.
+
+During actual execution, the order of operations done on fragments is always:
+
+* Alpha
+* Stencil
+* Depth
+
+Depth Members
+-------------
+
+enabled
+    Whether the depth test is enabled.
+writemask
+    Whether the depth buffer receives depth writes.
+func
+    The depth test function. One of PIPE_FUNC.
+
+Stencil Members
+---------------
+
+enabled
+    Whether the stencil test is enabled. For the second stencil, whether the
+    two-sided stencil is enabled. If two-sided stencil is disabled, the other
+    fields for the second array member are not valid.
+func
+    The stencil test function. One of PIPE_FUNC.
+valuemask
+    Stencil test value mask; this is ANDed with the value in the stencil
+    buffer and the reference value before doing the stencil comparison test.
+writemask
+    Stencil test writemask; this controls which bits of the stencil buffer
+    are written.
+fail_op
+    The operation to carry out if the stencil test fails. One of
+    PIPE_STENCIL_OP.
+zfail_op
+    The operation to carry out if the stencil test passes but the depth test
+    fails. One of PIPE_STENCIL_OP.
+zpass_op
+    The operation to carry out if the stencil test and depth test both pass.
+    One of PIPE_STENCIL_OP.
+
+Alpha Members
+-------------
+
+enabled
+    Whether the alpha test is enabled.
+func
+    The alpha test function. One of PIPE_FUNC.
+ref_value
+    Alpha test reference value; used for certain functions.