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 <axel.davy@ens.fr>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

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

@@ -127,6 +127,12 @@ offset_tri
 
 offset_units
     Specifies the polygon offset bias
+offset_units_unscaled
+    Specifies the unit of the polygon offset bias. If false, use the
+    GL/D3D1X behaviour. If true, offset_units is a floating point offset
+    which isn't scaled (D3D9). Note that GL/D3D1X behaviour has different
+    formula whether the depth buffer is unorm or float, which is not
+    the case for D3D9.
 offset_scale
     Specifies the polygon offset scale
 offset_clamp

src/gallium/docs/source/screen.rst

@@ -343,6 +343,8 @@ The integer capabilities:
 * ``PIPE_CAP_TGSI_VOTE``: Whether the ``VOTE_*`` ops can be used in shaders.
 * ``PIPE_CAP_MAX_WINDOW_RECTANGLES``: The maxium number of window rectangles
   supported in ``set_window_rectangles``.
+* ``PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED``: If true, the driver implements support
+  for ``pipe_rasterizer_state::offset_units_unscaled``.
 
 
 .. _pipe_capf:

src/gallium/drivers/freedreno/freedreno_screen.c

@@ -264,6 +264,7 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
 	case PIPE_CAP_TGSI_VOTE:
 	case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+	case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
 		return 0;
 
 	case PIPE_CAP_MAX_VIEWPORTS:

src/gallium/drivers/i915/i915_screen.c

@@ -275,6 +275,7 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
 
    case PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS:

src/gallium/drivers/ilo/ilo_screen.c

@@ -504,6 +504,7 @@ ilo_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -327,6 +327,7 @@ llvmpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
    }
    /* should only get here on unhandled cases */

src/gallium/drivers/nouveau/nv30/nv30_screen.c

@@ -198,6 +198,7 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/nouveau/nv50/nv50_screen.c

@@ -252,6 +252,7 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_ROBUST_BUFFER_ACCESS_BEHAVIOR:
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/nouveau/nvc0/nvc0_screen.c

@@ -263,6 +263,7 @@ nvc0_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_PCI_BUS:
    case PIPE_CAP_PCI_DEVICE:
    case PIPE_CAP_PCI_FUNCTION:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/r300/r300_screen.c

@@ -220,6 +220,7 @@ static int r300_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
         case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
         case PIPE_CAP_TGSI_VOTE:
         case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+        case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
             return 0;
 
         /* SWTCL-only features. */

src/gallium/drivers/r600/r600_pipe.c

@@ -370,6 +370,7 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
 	case PIPE_CAP_TGSI_VOTE:
 	case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+	case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
 		return 0;
 
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:

src/gallium/drivers/radeonsi/si_pipe.c

@@ -415,6 +415,7 @@ static int si_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
 	case PIPE_CAP_TGSI_VOTE:
 	case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+	case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
 		return 0;
 
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:

src/gallium/drivers/softpipe/sp_screen.c

@@ -277,6 +277,7 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
       return 4;

src/gallium/drivers/svga/svga_screen.c

@@ -410,6 +410,7 @@ svga_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
    }
 

src/gallium/drivers/swr/swr_screen.cpp

@@ -363,6 +363,7 @@ swr_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
    }
 

src/gallium/drivers/vc4/vc4_screen.c

@@ -213,6 +213,7 @@ vc4_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
         case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
         case PIPE_CAP_TGSI_VOTE:
         case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+        case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
                 return 0;
 
                 /* Stream output. */

src/gallium/drivers/virgl/virgl_screen.c

@@ -245,6 +245,7 @@ virgl_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES:
    case PIPE_CAP_TGSI_VOTE:
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
+   case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
       return 0;
    case PIPE_CAP_VENDOR_ID:
       return 0x1af4;

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)

src/gallium/include/pipe/p_state.h

@@ -139,6 +139,13 @@ 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.