Reviewed-by: Marek Olšák <marek.ol...@amd.com> Marek
On Tue, Aug 22, 2017 at 10:21 PM, Brian Paul <bri...@vmware.com> wrote: > Depending on which extension or GL spec you read the behavior of > glVertexAttrib(index=0) either sets the current value for generic > attribute 0, or it emits a vertex just like glVertex(). I believe > it should do either, depending on context (see below). > > The piglit gl-2.0-vertex-const-attr test declares two vertex attributes: > attribute vec2 vertex; > attribute vec4 attr; > and the GLSL linker assigns "vertex" to location 0 and "attr" to location 1. > The test passes. > > But if the declarations were reversed such that "attr" was location 0 and > "vertex" was location 1, the test would fail to draw properly. > > The problem is the call to glVertexAttrib(index=0) to set attr's value > was interpreted as glVertex() and did not set generic attribute[0]'s value. > Interesting, calling glVertex() outside glBegin/End (which is effectively > what the piglit test does) does not generate a GL error. > > I believe the behavior of glVertexAttrib(index=0) should depend on > whether it's called inside or outside of glBegin/glEnd(). If inside > glBegin/End(), it should act like glVertex(). Else, it should behave > like glVertexAttrib(index > 0). This seems to be what NVIDIA does. > > This patch makes two changes: > > 1. Check if we're inside glBegin/End for glVertexAttrib() > 2. Fix the vertex array binding for recalculate_input_bindings(). As it was, > we were using &vbo->currval[VBO_ATTRIB_POS], but that's interpreted > as a zero-stride attribute and doesn't make sense for array drawing. > > No Piglit regressions. Fixes updated gl-2.0-vertex-const-attr test and > passes new gl-2.0-vertex-attrib-0 test. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101941 > --- > src/mesa/vbo/vbo_attrib_tmp.h | 7 +++++-- > src/mesa/vbo/vbo_exec_array.c | 2 +- > 2 files changed, 6 insertions(+), 3 deletions(-) > > diff --git a/src/mesa/vbo/vbo_attrib_tmp.h b/src/mesa/vbo/vbo_attrib_tmp.h > index 5718ac5..126e4ef 100644 > --- a/src/mesa/vbo/vbo_attrib_tmp.h > +++ b/src/mesa/vbo/vbo_attrib_tmp.h > @@ -524,15 +524,18 @@ TAG(MultiTexCoord4fv)(GLenum target, const GLfloat * v) > > /** > * If index=0, does glVertexAttrib*() alias glVertex() to emit a vertex? > + * It depends on a few things, including whether we're inside or outside > + * of glBegin/glEnd. > */ > static inline bool > is_vertex_position(const struct gl_context *ctx, GLuint index) > { > - return index == 0 && _mesa_attr_zero_aliases_vertex(ctx); > + return (index == 0 && > + _mesa_attr_zero_aliases_vertex(ctx) && > + _mesa_inside_begin_end(ctx)); > } > > > - > static void GLAPIENTRY > TAG(VertexAttrib1fARB)(GLuint index, GLfloat x) > { > diff --git a/src/mesa/vbo/vbo_exec_array.c b/src/mesa/vbo/vbo_exec_array.c > index edd55ce..e3421fa 100644 > --- a/src/mesa/vbo/vbo_exec_array.c > +++ b/src/mesa/vbo/vbo_exec_array.c > @@ -356,7 +356,7 @@ recalculate_input_bindings(struct gl_context *ctx) > else if (array[VERT_ATTRIB_POS].Enabled) > inputs[0] = &vertexAttrib[VERT_ATTRIB_POS]; > else { > - inputs[0] = &vbo->currval[VBO_ATTRIB_POS]; > + inputs[0] = &vbo->currval[VBO_ATTRIB_GENERIC0]; > const_inputs |= VERT_BIT_POS; > } > > -- > 1.9.1 > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
