Re: [Mesa-dev] [PATCH 7/8] gallium: create TGSI_PROPERTY to disable viewport and clipping

Wed, 21 May 2014 03:42:33 -0700 

On 05/21/2014 12:49 AM, Marek Olšák wrote:

Hi,

Could somebody from VMWare please review this patch? It's for st/nine
(open d3d9 state tracker).

Thanks,

Marek

On Sat, May 17, 2014 at 1:20 AM, Automated rebase
<david.heidelber...@ixit.cz> wrote:

From: Christoph Bumiller <e0425...@student.tuwien.ac.at>

---
  src/gallium/auxiliary/tgsi/tgsi_strings.c  |  3 ++-
  src/gallium/auxiliary/tgsi/tgsi_ureg.c     | 16 ++++++++++++++++
  src/gallium/auxiliary/tgsi/tgsi_ureg.h     |  4 ++++
  src/gallium/docs/source/tgsi.rst           |  9 +++++++++
  src/gallium/include/pipe/p_shader_tokens.h |  3 ++-
  5 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/gallium/auxiliary/tgsi/tgsi_strings.c 
b/src/gallium/auxiliary/tgsi/tgsi_strings.c
index 5b6e47f..c3e7118 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_strings.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_strings.c
@@ -120,7 +120,8 @@ const char *tgsi_property_names[TGSI_PROPERTY_COUNT] =
     "FS_COORD_PIXEL_CENTER",
     "FS_COLOR0_WRITES_ALL_CBUFS",
     "FS_DEPTH_LAYOUT",
-   "VS_PROHIBIT_UCPS"
+   "VS_PROHIBIT_UCPS",
+   "VS_POSITION_WINDOW_SPACE"
  };

  const char *tgsi_type_names[5] =
diff --git a/src/gallium/auxiliary/tgsi/tgsi_ureg.c 
b/src/gallium/auxiliary/tgsi/tgsi_ureg.c
index 2bf93ee..bd0a3f7 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_ureg.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_ureg.c
@@ -173,6 +173,7 @@ struct ureg_program
     unsigned char property_fs_coord_pixel_center; /* = 
TGSI_FS_COORD_PIXEL_CENTER_* */
     unsigned char property_fs_color0_writes_all_cbufs; /* = 
TGSI_FS_COLOR0_WRITES_ALL_CBUFS * */
     unsigned char property_fs_depth_layout; /* TGSI_FS_DEPTH_LAYOUT */
+   boolean property_vs_window_space_position; /* TGSI_VS_WINDOW_SPACE_POSITION 
*/

     unsigned nr_addrs;
     unsigned nr_preds;
@@ -331,6 +332,13 @@ ureg_property_fs_depth_layout(struct ureg_program *ureg,
     ureg->property_fs_depth_layout = fs_depth_layout;
  }

+void
+ureg_property_vs_window_space_position(struct ureg_program *ureg,
+                                       boolean vs_window_space_position)
+{
+   ureg->property_vs_window_space_position = vs_window_space_position;
+}
+
  struct ureg_src
  ureg_DECL_fs_input_cyl_centroid(struct ureg_program *ureg,
                         unsigned semantic_name,
@@ -1508,6 +1516,14 @@ static void emit_decls( struct ureg_program *ureg )
                      ureg->property_fs_depth_layout);
     }

+   if (ureg->property_vs_window_space_position) {
+      assert(ureg->processor == TGSI_PROCESSOR_VERTEX);
+
+      emit_property(ureg,
+                    TGSI_PROPERTY_VS_WINDOW_SPACE_POSITION,
+                    ureg->property_vs_window_space_position);
+   }
+
     if (ureg->processor == TGSI_PROCESSOR_VERTEX) {
        for (i = 0; i < UREG_MAX_INPUT; i++) {
           if (ureg->vs_inputs[i/32] & (1 << (i%32))) {
diff --git a/src/gallium/auxiliary/tgsi/tgsi_ureg.h 
b/src/gallium/auxiliary/tgsi/tgsi_ureg.h
index a0a50b7..28edea6 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_ureg.h
+++ b/src/gallium/auxiliary/tgsi/tgsi_ureg.h
@@ -184,6 +184,10 @@ void
  ureg_property_fs_depth_layout(struct ureg_program *ureg,
                                unsigned fs_depth_layout);

+void
+ureg_property_vs_window_space_position(struct ureg_program *ureg,
+                                       boolean vs_window_space_position);
+

  /***********************************************************************
   * Build shader declarations:
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index 9500b9d..2ca3c3b 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -2848,6 +2848,15 @@ input primitive. Each invocation will have a different
  TGSI_SEMANTIC_INVOCATIONID system value set. If not specified, assumed to
  be 1.

+VS_WINDOW_SPACE_POSITION
+""""""""""""""""""""""""""
+If this property is set on the vertex shader, the TGSI_SEMANTIC_POSITION output
+is assumed to contain window space coordinates.
+Division of X,Y,Z by W and the viewport transformation are disabled, and 1/W is
+directly taken from the 4-th component of the shader output.
+Naturally, clipping is not performed on window coordinates either.
+The effect of this property is undefined if a geometry or tessellation shader
+are in use.

  Texture Sampling and Texture Formats
  ------------------------------------
diff --git a/src/gallium/include/pipe/p_shader_tokens.h 
b/src/gallium/include/pipe/p_shader_tokens.h
index d095bd3..9261b79 100644
--- a/src/gallium/include/pipe/p_shader_tokens.h
+++ b/src/gallium/include/pipe/p_shader_tokens.h
@@ -237,7 +237,8 @@ union tgsi_immediate_data
  #define TGSI_PROPERTY_FS_DEPTH_LAYOUT        6
  #define TGSI_PROPERTY_VS_PROHIBIT_UCPS       7
  #define TGSI_PROPERTY_GS_INVOCATIONS         8
-#define TGSI_PROPERTY_COUNT                  9
+#define TGSI_PROPERTY_VS_WINDOW_SPACE_POSITION 9
+#define TGSI_PROPERTY_COUNT                  10

  struct tgsi_property {
     unsigned Type         : 4;  /**< TGSI_TOKEN_TYPE_PROPERTY */
--
I can't say I'm a big fan of it (I guess alternatively you could use a TGSI_SEMANTIC_POSITIONT output but that doesn't really make a difference neither). This was quite some d3d hack which doesn't really fit into a modern shader based world (of course, it doesn't work with d3d10 neither). So, the usual way to deal with this is to translate this away, since this was only used for old or simple stuff afaik (if it was complex you tend to not already know the screen space coords) noone is going to care if it runs at 1500 or 1520 fps anyway. But if you really think this is a must have and are going to use it in a public state tracker you probably have to implement a cap bit for it too, and be able to deal with drivers which can't handle it - it seems unreasonable to me to assume all drivers will handle it (hence you don't really save anything in the state tracker, you still need all the code translating it away anyway). 

Roland
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