From 54826331b31d4cdcb3a7e444caf97b75c3364b54 Mon Sep 17 00:00:00 2001 From: "Juan A. Suarez Romero" Date: Fri, 7 Jul 2017 09:35:52 +0000 Subject: [PATCH] glsl: xfb_stride applies to buffers, not block members MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When we have an interface block like: layout (xfb_buffer = 0, xfb_offset = 0) out Block { vec4 var1; layout (xfb_stride = 48) vec4 var2; vec4 var3; }; According to ARB_enhanced_layouts spec: "The *xfb_stride* qualifier specifies how many bytes are consumed by each captured vertex. It applies to the transform feedback buffer for that declaration, whether it is inherited or explicitly declared. It can be applied to variables, blocks, block members, or just the qualifier out. [ ...] While *xfb_stride* can be declared multiple times for the same buffer, it is a compile-time or link-time error to have different values specified for the stride for the same buffer." This means xfb_stride actually applies to the buffer, and not to the individual components. In the above example, it means that var2 consumes 16 bytes, and var3 is at offset 32. This has been confirmed also by John Kessenich, the main contact for the ARB_enhanced_layouts specs, and also because this commit fixes: GL45.enhanced_layouts.xfb_block_member_stride This commit is in practice a revert of 598790e8564 (glsl: apply xfb_stride to implicit offsets for ifc block members). Reviewed-by: Timothy Arceri Reviewed-by: Nicolai Hähnle --- src/compiler/glsl/ast_to_hir.cpp | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp index 4916b1590a0..ee806052326 100644 --- a/src/compiler/glsl/ast_to_hir.cpp +++ b/src/compiler/glsl/ast_to_hir.cpp @@ -7372,14 +7372,13 @@ ast_process_struct_or_iface_block_members(exec_list *instructions, qual->offset, &xfb_offset)) { fields[i].offset = xfb_offset; block_xfb_offset = fields[i].offset + - MAX2(xfb_stride, (int) (4 * field_type->component_slots())); + 4 * field_type->component_slots(); } } else { if (layout && layout->flags.q.explicit_xfb_offset) { unsigned align = field_type->is_64bit() ? 8 : 4; fields[i].offset = glsl_align(block_xfb_offset, align); - block_xfb_offset += - MAX2(xfb_stride, (int) (4 * field_type->component_slots())); + block_xfb_offset += 4 * field_type->component_slots(); } } -- 2.30.2