From 066fb237e642ec5ebe2c86f89753cba1ad389410 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Sat, 26 Oct 2013 11:34:11 -0700 Subject: [PATCH] i965: Add support for gl_SkipComponents[1234]. ARB_transform_feedback3 allows applications to insert blank space between interleaved varyings by adding fake 1, 2, 3, or 4-component varyings named gl_SkipComponents[1234]. Mesa's core data structures don't explicitly track these, instead simply tracking the buffer offset for each real varying. If there is padding due to gl_SkipComponents, these will not be contiguous. Our hardware takes the specification quite literally. Instead of specifying offsets for each varying, it assumes they're all contiguous and requires you to program fake varyings for each "hole". This patch adds support for emitting SO_DECL structures for these holes. Although we've lost the information about exactly how the application specified their padding (i.e. gl_SkipComponents2, gl_SkipComponents2 vs. a single gl_SkipComponents4), it shouldn't matter. We just need to emit the right amount of space. This patch emits the minimal number of hole SO_DECL structures. Signed-off-by: Kenneth Graunke Reviewed-by: Ian Romanick --- src/mesa/drivers/dri/i965/gen7_sol_state.c | 23 ++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/src/mesa/drivers/dri/i965/gen7_sol_state.c b/src/mesa/drivers/dri/i965/gen7_sol_state.c index b192d5d6c03..8ef899306a0 100644 --- a/src/mesa/drivers/dri/i965/gen7_sol_state.c +++ b/src/mesa/drivers/dri/i965/gen7_sol_state.c @@ -140,9 +140,28 @@ gen7_upload_3dstate_so_decl_list(struct brw_context *brw, SO_DECL_REGISTER_INDEX_SHIFT; decl |= component_mask << SO_DECL_COMPONENT_MASK_SHIFT; - /* This assert should be true until GL_ARB_transform_feedback_instanced - * is added and we start using the hole flag. + /* Mesa doesn't store entries for gl_SkipComponents in the Outputs[] + * array. Instead, it simply increments DstOffset for the following + * input by the number of components that should be skipped. + * + * Our hardware is unusual in that it requires us to program SO_DECLs + * for fake "hole" components, rather than simply taking the offset + * for each real varying. Each hole can have size 1, 2, 3, or 4; we + * program as many size = 4 holes as we can, then a final hole to + * accomodate the final 1, 2, or 3 remaining. */ + int skip_components = + linked_xfb_info->Outputs[i].DstOffset - next_offset[buffer]; + + next_offset[buffer] += skip_components; + + while (skip_components >= 4) { + so_decl[decls++] = SO_DECL_HOLE_FLAG | 0xf; + skip_components -= 4; + } + if (skip_components > 0) + so_decl[decls++] = SO_DECL_HOLE_FLAG | ((1 << skip_components) - 1); + assert(linked_xfb_info->Outputs[i].DstOffset == next_offset[buffer]); next_offset[buffer] += components; -- 2.30.2