src/gallium/docs/source/cso/dsa.rst

   1 .. _depth,stencil,&alpha:
   2
   3 Depth, Stencil, & Alpha
   4 =======================
   5
   6 These three states control the depth, stencil, and alpha tests, used to
   7 discard fragments that have passed through the fragment shader.
   8
   9 Traditionally, these three tests have been clumped together in hardware, so
  10 they are all stored in one structure.
  11
  12 During actual execution, the order of operations done on fragments is always:
  13
  14 * Alpha
  15 * Stencil
  16 * Depth
  17
  18 Depth Members
  19 -------------
  20
  21 enabled
  22     Whether the depth test is enabled.
  23 writemask
  24     Whether the depth buffer receives depth writes.
  25 func
  26     The depth test function. One of PIPE_FUNC.
  27
  28 Stencil Members
  29 ---------------
  30
  31 enabled
  32     Whether the stencil test is enabled. For the second stencil, whether the
  33     two-sided stencil is enabled. If two-sided stencil is disabled, the other
  34     fields for the second array member are not valid.
  35 func
  36     The stencil test function. One of PIPE_FUNC.
  37 valuemask
  38     Stencil test value mask; this is ANDed with the value in the stencil
  39     buffer and the reference value before doing the stencil comparison test.
  40 writemask
  41     Stencil test writemask; this controls which bits of the stencil buffer
  42     are written.
  43 fail_op
  44     The operation to carry out if the stencil test fails. One of
  45     PIPE_STENCIL_OP.
  46 zfail_op
  47     The operation to carry out if the stencil test passes but the depth test
  48     fails. One of PIPE_STENCIL_OP.
  49 zpass_op
  50     The operation to carry out if the stencil test and depth test both pass.
  51     One of PIPE_STENCIL_OP.
  52
  53 Alpha Members
  54 -------------
  55
  56 enabled
  57     Whether the alpha test is enabled.
  58 func
  59     The alpha test function. One of PIPE_FUNC.
  60 ref_value
  61     Alpha test reference value; used for certain functions.