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authorBrian Paul <brianp@vmware.com>2017-08-18 21:03:16 -0600
committerBrian Paul <brianp@vmware.com>2017-08-24 07:36:10 -0600
commitfe2f5cfdc7439cbe481d4bea393b46395967a8a3 (patch)
tree1adb3ea286488795c95a861d10ca8d67a21b1d27 /src
parenta7e65a443f8aebd40b573a1e16375193c21c36cc (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.h7
-rw-r--r--src/mesa/vbo/vbo_exec_array.c2
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;
}