gallium: Add a cap for offset_units_unscaled

D3D9 has a different behaviour for depth bias.

For OGL/D3D1X, the depth bias unit is the
minimal resolvable value for the depth buffer,
which depends on the format (and has different
behaviour for float depth buffers).

For D3D9, the depth bias unit is 1.0f.

Signed-off-by: Axel Davy <[email protected]>
Reviewed-by: Marek Olšák <[email protected]>

2 files changed, 8 insertions, 0 deletions

diff --git a/src/gallium/include/pipe/p_defines.h b/src/gallium/include/pipe/p_defines.h
index c46ac5a6a63..62fa67374f2 100644
--- a/src/gallium/include/pipe/p_defines.h
+++ b/src/gallium/include/pipe/p_defines.h
@@ -731,6 +731,7 @@ enum pipe_cap
    PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES,
    PIPE_CAP_TGSI_VOTE,
    PIPE_CAP_MAX_WINDOW_RECTANGLES,
+   PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED,
 };
 
 #define PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 (1 << 0)
diff --git a/src/gallium/include/pipe/p_state.h b/src/gallium/include/pipe/p_state.h
index 9c693555c7e..1543e90972e 100644
--- a/src/gallium/include/pipe/p_state.h
+++ b/src/gallium/include/pipe/p_state.h
@@ -140,6 +140,13 @@ struct pipe_rasterizer_state
    unsigned clip_halfz:1;
 
    /**
+    * When true do not scale offset_units and use same rules for unorm and
+    * float depth buffers (D3D9). When false use GL/D3D1X behaviour.
+    * This depends on PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED.
+    */
+   unsigned offset_units_unscaled:1;
+
+   /**
     * Enable bits for clipping half-spaces.
     * This applies to both user clip planes and shader clip distances.
     * Note that if the bound shader exports any clip distances, these