• Create Account

glClearBufferData- How to Use It?

Old topic!

Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.

#1SHOKWAV  Members

Posted 11 December 2012 - 07:24 PM

Hello, I need to learn the proper usage for glClearBufferData for an application I'm creating. I've looked at the official documentation... which isn't very descriptive, mainly what I don't understand are the internalformat, format, and type parameters.

void glClearBufferData( GLenum target,
GLenum internalformat,
GLenum format,
GLenum type,
const void * data);

I have a buffer with a target and some data, and all the data are in float form. I want to clear it all out to 0. Question is, how? Which one do I specify that it's in floats? Internalformat? What about the format and type? I just want to clear out all the memory. I know to specify NULL for data... but what about format and type?

#2santa01  Members

Posted 13 December 2012 - 11:57 AM

You can look through the http://www.opengl.or...ffer_object.txt document, they got some explanation there:

	To fill all or part of an existing buffer object's data store with a
constant value, call
void ClearBufferSubData(enum target,
enum internalformat,
enum format,
enum type,
sizeiptr offset,
sizeiptr size,
const void * data);
with <target> set to the target to which the destination buffer is bound.
<target> must be one of the targets listed in Table 2.8.
<internalformat> must be set to one of the format tokens listed in Table
3.15, "Internal formats for buffer textures". <format> and <type> specify
the format and type of the source data and are interpreted as described in
Section 3.7.2. <offset> set to the offset, measured in basic
machine units, into the buffer object's data store from which to begin
filling, and <size> set to the size, also in basic machine units, of the
range to fill. Both <offset> and <range> must be multiples of the number
of basic machine units per-element for that internal format specified by
<internalformat>, otherwise the error INVALID_VALUE is generated.
<data> is a pointer to an array of between one and four components
containing the data to be used as the source of the constant fill value.
The elements of <data> are converted by the GL into the format specified by
<internalformat> in the manner described in section 2.3.1, and then used to
fill the specified range of the destination buffer. If <data> is NULL, then
the pointer is ignored and the sub-range of the buffer is filled with zeros.
If <offset> or <size> is less than zero, or if <offset> + <size> is
greater than the value of BUFFER_SIZE for the buffer bound to <target>
then the error INVALID_VALUE is generated. The command
An INVALID_OPERATION error is generated if any part of the specified
range of the buffer bound to <target> is currently mapped.
void ClearBufferData(enum target,
enum internalformat,
enum format,
enum type,
const void * data);
is equivalent to calling ClearBufferSubData with <target>,
<internalformat> and <data> as specified, with <offset> set to zero,
and <size> set to the value of BUFFER_SIZE for the buffer bound to
<target>.


Old topic!

Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.