Message: 1
Date: Mon, 27 Sep 2004 01:39:54 -0700
From: Ron Avitzur <email@hidden>
Subject: vertex buffer objects
To: email@hidden
Message-ID: <p0610050abd7d8253d0ab@[192.168.1.100]>
Content-Type: text/plain; charset="us-ascii" ; format="flowed"
Hello,
My application is exhibiting some difficult to diagnose bugs which show
up only when rendering using vertex buffer objects using glColorPointer
on machines with nVidia video.
Since this is both new code, and the first time I've used VBOs, there
are many possibilities where I may have misunderstood something and
introduced the problem. At the moment I'm developing on machines
with Radeon chips which do not exhibit the bug, making it more
difficult to diagnose. One possibility I am unsure of from reading
the VBO spec, is whether the problem could be caused by using one
VBO for the vertex and normal data, and another VBO for the color
array data.
Is that something which I should only expect to work on ATI chips?
int stride = sizeof(Vertex) * (fInterleaved ? 2 : 1);
int normalsOffset = sizeof(Vertex) * (fInterleaved ? 1 : fNumVertices);
glBindBufferARB(GL_ELEMENT_ARRAY_BUFFER_ARB, fIndexBufferObjectID);
glBindBufferARB(GL_ARRAY_BUFFER_ARB, fVertexBufferObjectID);
glVertexPointer(3, GL_FLOAT, stride, (char*)NULL + 0);
if (fUseNormals) {
glEnableClientState(GL_NORMAL_ARRAY);
glNormalPointer(GL_FLOAT, stride, (char*)NULL + normalsOffset);
}
if (fColorBufferObjectID) {
glBindBufferARB(GL_ARRAY_BUFFER_ARB, fColorBufferObjectID);
glColorPointer(3, GL_FLOAT, sizeof(ColorArrayElement), NULL);
}
Is anyone here aware of differences in implementation or support
with respect to vertex buffer objects between ATI and nVidia that
might help me narrow down diagnosing the problem?
Best regards,
Ron Avitzur
------------------------------
Message: 2
Date: Mon, 27 Sep 2004 11:36:08 -0700
From: Ron Avitzur <email@hidden>
Subject: multiple vertex buffer objects
To: email@hidden
Message-ID: <p06100514bd7e0c9662fe@[192.168.1.100]>
Content-Type: text/plain; charset="us-ascii" ; format="flowed"
Hello,
I tried putting all the array data into one vertex buffer object,
and that seems to have fixed the problem I was seeing. So my next
questions, in an attempt to tell if I've actually corrected the bug,
or merely made it more difficult to reproduce:
1. Does the spec require implementations to support code such as that
below, which binds one VBO before calling glVertexPointer, then
binds another VBO before calling glColorPointer, and the calls
glDrawElements?
2. If that is allowed by the spec, have I hit a known problem with
the nVidia drivers on 10.3.5 or might I have made some other
errors as well which I should investigate?
Before I report this, I'd like to know if it is actually a bug,
or if I've merely misinterpreted the VBO spec.
Best regards,
Ron Avitzur
My application is exhibiting some difficult to diagnose bugs which show
up only when rendering using vertex buffer objects using glColorPointer
on machines with nVidia video.
Since this is both new code, and the first time I've used VBOs, there
are many possibilities where I may have misunderstood something and
introduced the problem. At the moment I'm developing on machines
with Radeon chips which do not exhibit the bug, making it more
difficult to diagnose. One possibility I am unsure of from reading
the VBO spec, is whether the problem could be caused by using one
VBO for the vertex and normal data, and another VBO for the color
array data.
Is that something which I should only expect to work on ATI chips?
int stride = sizeof(Vertex) * (fInterleaved ? 2 : 1);
int normalsOffset = sizeof(Vertex) * (fInterleaved ? 1 : fNumVertices);
glBindBufferARB(GL_ELEMENT_ARRAY_BUFFER_ARB, fIndexBufferObjectID);
glBindBufferARB(GL_ARRAY_BUFFER_ARB, fVertexBufferObjectID);
glVertexPointer(3, GL_FLOAT, stride, (char*)NULL + 0);
if (fUseNormals) {
glEnableClientState(GL_NORMAL_ARRAY);
glNormalPointer(GL_FLOAT, stride, (char*)NULL + normalsOffset);
}
if (fColorBufferObjectID) {
glBindBufferARB(GL_ARRAY_BUFFER_ARB, fColorBufferObjectID);
glColorPointer(3, GL_FLOAT, sizeof(ColorArrayElement), NULL);
}
Is anyone here aware of differences in implementation or support
with respect to vertex buffer objects between ATI and nVidia that
might help me narrow down diagnosing the problem?
------------------------------
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