2010/9/14 Chia-I Wu <olva...@gmail.com>: > 2010/9/14 Kristian Høgsberg <k...@bitplanet.net>: >> 2010/9/13 keith whitwell <keith.whitw...@gmail.com>: >>> Hey Kristian, >>> >>> The first question is whether this is necessary - from vague memory I >>> have an idea that current attributes need not be updated by vertex >>> buffer rendering - ie. it's optional/implementation-dependent. >>> >>> I assume you're concerned with the case where you have something like >>> >>> // ctx->Current.Color is xyz >>> >>> glDrawArrays(); >>> >>> // has ctx->Current.Color been updated?? >>> >>> But assuming I'm wrong about that & we really do want to make >>> DrawArrays set the current values, the patch looks good... >> >> No, what I'm seeing is that the code in question sets three generic >> vertex attributes and then calls glDrawArrays(). The value of the >> last attribute is not propagates into the shader. >> >> The problem is that the vertex array code keeps the values in >> exec->vtx.vertex, but the implementation of glDrawArrays looks in >> ctx->Current (that's what I assume, I didn't track that down). When >> the code hits a case where the size of an attribute is smaller that >> what we're trying to set, it recomputes the layout of the >> exec->vtx.vertex values and as a side effect copies the >> exec->vtx.vertex values to ctx->Current. Since we start out with >> attrsz == 0 for all attributes, each new attribute will trigger this >> recomputation and thus effectively flushes all previous values to >> ctx->Current. Which is why all but the last attribute make it to the >> shader. >> >> Note that the ATTR macro is defined differently, depending on >> FEATURE_beginend - the !FEATURE_beginend case sets the >> FLUSH_UPDATE_CURRENT flag too. I don't know why we wouldn't also set >> it in the FEATURE_beginend case, not using begin/end in that case is >> still an option. > The way glColor4f is dispatched depends on whether it is GL or ES: > > GL (with FEATURE_beginend): glColor4f -> neutral_Color4f -> vbo_Color4f > ES (w/o FEATURE_beginend): glColor4f -> _es_Color4f -> vbo_Color4f > > In the former case, FLUSH_UPDATE_CURRENT should have been set by > vbo_exec_BeginVertices which is called by neutral_Color4f. In the latter > case, > the flag must be set in vbo_Color4f. Could it be a bug some where in vtxfmt? > > One issue I noticed just last week is that the current scheme does not take > into account "ES with FEATURE_beginend". This happens with --enable-gles2 > build. Since FEATURE_beginend is enabled in such build, vbo_Color4f does not > set FLUSH_UPDATE_CURRENT. Yet, an ES context does not use neutral_Color4f.
And that's exactly the problem I have. Setting FLUSH_UPDATE_CURRENT in the ATTR macro makes sure that the FLUSH_CURRENT in vbo_exec_DrawArrays (and other array draw funcs) ends up calling vbo_exec_copy_to_current(), which then pushes the values into ctx->Current before the draw call. I don't see a problem with this approach; in a begin/end, this flag is already set, so there's no overhead, outside begin/end (ES2) it's required for correct behaviour. Kristian _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
