diff options
author | Brian Paul <brianp@vmware.com> | 2017-08-18 21:03:16 -0600 |
---|---|---|
committer | Brian Paul <brianp@vmware.com> | 2017-08-24 07:36:10 -0600 |
commit | fe2f5cfdc7439cbe481d4bea393b46395967a8a3 (patch) | |
tree | 1adb3ea286488795c95a861d10ca8d67a21b1d27 /src | |
parent | a7e65a443f8aebd40b573a1e16375193c21c36cc (diff) |
vbo: fix glVertexAttrib(index=0)
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
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Charmaine Lee <charmainel@vmware.com>
Diffstat (limited to 'src')
-rw-r--r-- | src/mesa/vbo/vbo_attrib_tmp.h | 7 | ||||
-rw-r--r-- | 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 5718ac5a092..126e4ef0d6e 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 edd55ce69e2..e3421fa9b51 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; } |