gallium: add PIPE_CAP_TEXRECT

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8898>

docs/gallium/screen.rst

@@ -611,6 +611,7 @@ The integer capabilities:
 * ``PIPE_CAP_DEVICE_PROTECTED_CONTENT``: Whether the device support protected / encrypted content.
 * ``PIPE_CAP_PREFER_REAL_BUFFER_IN_CONSTBUF0``: The state tracker is encouraged to upload constants into a real buffer and bind it into constant buffer 0 instead of binding a user pointer. This may enable a faster codepath in a gallium frontend for drivers that really prefer a real buffer.
 * ``PIPE_CAP_GL_CLAMP``: Driver natively supports GL_CLAMP.  Required for non-NIR drivers with the GL frontend.  NIR drivers with the cap unavailable will have GL_CLAMP lowered to txd/txl with a saturate on the coordinates.
+* ``PIPE_CAP_TEXRECT``: Driver supports rectangle textures.  Required for OpenGL on `!prefers_nir` drivers.  If this cap is not present, st/mesa will lower the NIR to use normal 2D texture sampling by using either `txs` or `nir_intrinsic_load_texture_scaling` to normalize the texture coordinates.
 
 .. _pipe_capf:
 

src/gallium/auxiliary/util/u_screen.c

@@ -453,6 +453,9 @@ u_pipe_screen_get_param_defaults(struct pipe_screen *pscreen,
    case PIPE_CAP_PREFER_REAL_BUFFER_IN_CONSTBUF0:
       return 0;
 
+   case PIPE_CAP_TEXRECT:
+      return 1;
+
    case PIPE_CAP_SHADER_ATOMIC_INT64:
       return 0;
 

src/gallium/include/pipe/p_defines.h

@@ -978,6 +978,8 @@ enum pipe_cap
    PIPE_CAP_DEVICE_PROTECTED_CONTENT,
    PIPE_CAP_PREFER_REAL_BUFFER_IN_CONSTBUF0,
    PIPE_CAP_GL_CLAMP,
+   PIPE_CAP_TEXRECT,
+
    PIPE_CAP_LAST,
    /* XXX do not add caps after PIPE_CAP_LAST! */
 };