[Mesa-dev] [PATCH] i965: handle gl_PointCoord for Gen4 and Gen5 platforms
Yuanhan Liu
yuanhan.liu at linux.intel.com
Sun Feb 26 23:46:32 PST 2012
This patch add the support of gl_PointCoord gl builtin variable for
platform gen4 and gen5(ILK).
Unlike gen6+, we don't have a hardware support of gl_PointCoord, means
hardware will not calculate the interpolation coefficient for you.
Instead, you should handle it yourself in sf shader stage.
But badly, gl_PointCoord is a FS instead of VS builtin variable, thus
it's not included in c.vue_map generated in VS stage. Thus the current
code doesn't aware of this attribute. And to handle it correctly, we
need add it to c.vue_map manually to let SF shader generate the needed
interpolation coefficient for FS shader. SF stage has it's own copy of
vue_map, thus I think it's safe to do it manually.
Since handling gl_PointCoord for gen4 and gen5 platforms is somehow a
little special, I added a lot of comments and hope I didn't overdo it ;)
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=45975
Piglit: glsl-fs-pointcoord and fbo-gl_pointcoord
NOTE: This is a candidate for stable release branches.
Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
---
src/mesa/drivers/dri/i965/brw_context.h | 6 ++++++
src/mesa/drivers/dri/i965/brw_fs.cpp | 9 +++++++++
src/mesa/drivers/dri/i965/brw_sf.c | 26 ++++++++++++++++++++++----
src/mesa/drivers/dri/i965/brw_sf.h | 1 +
src/mesa/drivers/dri/i965/brw_sf_emit.c | 4 ++++
5 files changed, 42 insertions(+), 4 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index 09d8373..7c794ad 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -296,6 +296,12 @@ typedef enum
BRW_VERT_RESULT_NDC = VERT_RESULT_MAX,
BRW_VERT_RESULT_HPOS_DUPLICATE,
BRW_VERT_RESULT_PAD,
+ /*
+ * It's actually not a vert_result but just a _mark_ to let sf aware that
+ * he need do something special to handle gl_PointCoord builtin variable
+ * correctly. see compile_sf_prog() for more info.
+ */
+ BRW_VERT_RESULT_PNTC,
BRW_VERT_RESULT_MAX
} brw_vert_result;
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index bf59da3..5f3d79d 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -710,6 +710,15 @@ fs_visitor::calculate_urb_setup()
urb_setup[fp_index] = urb_next++;
}
}
+
+ /*
+ * It's a FS only attribute, and we did interpolation for this attribute
+ * in SF thread. So, count it here, too.
+ *
+ * See compile_sf_prog() for more info.
+ */
+ if (brw->fragment_program->Base.InputsRead & BITFIELD64_BIT(FRAG_ATTRIB_PNTC))
+ urb_setup[FRAG_ATTRIB_PNTC] = urb_next++;
}
/* Each attribute is 4 setup channels, each of which is half a reg. */
diff --git a/src/mesa/drivers/dri/i965/brw_sf.c b/src/mesa/drivers/dri/i965/brw_sf.c
index 6e63583..7950c47 100644
--- a/src/mesa/drivers/dri/i965/brw_sf.c
+++ b/src/mesa/drivers/dri/i965/brw_sf.c
@@ -64,6 +64,16 @@ static void compile_sf_prog( struct brw_context *brw,
c.key = *key;
c.vue_map = brw->vs.prog_data->vue_map;
+ if (c.key.do_point_coord) {
+ /*
+ * gl_PointCoord is a FS instead of VS builtin variable, thus it's
+ * not included in c.vue_map generated in VS stage. Here we add
+ * it manually to let SF shader generate the needed interpolation
+ * coefficient for FS shader.
+ */
+ c.vue_map.vert_result_to_slot[BRW_VERT_RESULT_PNTC] = c.vue_map.num_slots;
+ c.vue_map.slot_to_vert_result[c.vue_map.num_slots++] = BRW_VERT_RESULT_PNTC;
+ }
c.urb_entry_read_offset = brw_sf_compute_urb_entry_read_offset(intel);
c.nr_attr_regs = (c.vue_map.num_slots + 1)/2 - c.urb_entry_read_offset;
c.nr_setup_regs = c.nr_attr_regs;
@@ -125,6 +135,7 @@ brw_upload_sf_prog(struct brw_context *brw)
{
struct gl_context *ctx = &brw->intel.ctx;
struct brw_sf_prog_key key;
+ bool render_to_fbo = ctx->DrawBuffer->Name != 0;
memset(&key, 0, sizeof(key));
@@ -167,7 +178,15 @@ brw_upload_sf_prog(struct brw_context *brw)
key.point_sprite_coord_replace |= (1 << i);
}
}
- key.sprite_origin_lower_left = (ctx->Point.SpriteOrigin == GL_LOWER_LEFT);
+ if (brw->fragment_program->Base.InputsRead & BITFIELD64_BIT(FRAG_ATTRIB_PNTC))
+ key.do_point_coord = 1;
+ /*
+ * Window coordinates in a FBO are inverted, which means point
+ * sprite origin must be inverted, too.
+ */
+ if ((ctx->Point.SpriteOrigin == GL_LOWER_LEFT) != render_to_fbo)
+ key.sprite_origin_lower_left = true;
+
/* _NEW_LIGHT */
key.do_flat_shading = (ctx->Light.ShadeModel == GL_FLAT);
key.do_twoside_color = (ctx->Light.Enabled && ctx->Light.Model.TwoSide);
@@ -176,10 +195,9 @@ brw_upload_sf_prog(struct brw_context *brw)
if (key.do_twoside_color) {
/* If we're rendering to a FBO, we have to invert the polygon
* face orientation, just as we invert the viewport in
- * sf_unit_create_from_key(). ctx->DrawBuffer->Name will be
- * nonzero if we're rendering to such an FBO.
+ * sf_unit_create_from_key().
*/
- key.frontface_ccw = (ctx->Polygon.FrontFace == GL_CCW) ^ (ctx->DrawBuffer->Name != 0);
+ key.frontface_ccw = (ctx->Polygon.FrontFace == GL_CCW) != render_to_fbo;
}
if (!brw_search_cache(&brw->cache, BRW_SF_PROG,
diff --git a/src/mesa/drivers/dri/i965/brw_sf.h b/src/mesa/drivers/dri/i965/brw_sf.h
index 4ef0240..f908fc0 100644
--- a/src/mesa/drivers/dri/i965/brw_sf.h
+++ b/src/mesa/drivers/dri/i965/brw_sf.h
@@ -52,6 +52,7 @@ struct brw_sf_prog_key {
GLuint do_flat_shading:1;
GLuint frontface_ccw:1;
GLuint do_point_sprite:1;
+ GLuint do_point_coord:1;
GLuint sprite_origin_lower_left:1;
GLuint userclip_active:1;
};
diff --git a/src/mesa/drivers/dri/i965/brw_sf_emit.c b/src/mesa/drivers/dri/i965/brw_sf_emit.c
index 1ee0098..ff6383b 100644
--- a/src/mesa/drivers/dri/i965/brw_sf_emit.c
+++ b/src/mesa/drivers/dri/i965/brw_sf_emit.c
@@ -386,6 +386,8 @@ calculate_point_sprite_mask(struct brw_sf_compile *c, GLuint reg)
if (c->key.point_sprite_coord_replace & (1 << (vert_result1 - VERT_RESULT_TEX0)))
pc |= 0x0f;
}
+ if (vert_result1 == BRW_VERT_RESULT_PNTC)
+ pc |= 0x0f;
vert_result2 = vert_reg_to_vert_result(c, reg, 1);
if (vert_result2 >= VERT_RESULT_TEX0 && vert_result2 <= VERT_RESULT_TEX7) {
@@ -393,6 +395,8 @@ calculate_point_sprite_mask(struct brw_sf_compile *c, GLuint reg)
VERT_RESULT_TEX0)))
pc |= 0xf0;
}
+ if (vert_result2 == BRW_VERT_RESULT_PNTC)
+ pc |= 0xf0;
return pc;
}
--
1.7.4.4
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