site_archiver@lists.apple.com Delivered-To: pro-apps-dev@lists.apple.com I should clarify that if you do what I suggest below, you don't need any temporary buffers. Just texture your quads with the input texture and they're automatically drawn to the output texture when you do any normal drawing. Darrin On Aug 18, 2011, at 2:44 PM, Darrin Cardani wrote:

On Aug 18, 2011, at 11:31 AM, Martin Baker wrote:

...

Having passed the first hurdle and successfully managed to draw lines and rectangles (DH_GridX and DH_WideSafeX released yesterday) we move on to other things. In converting one of our FxScript filters, the aim is to write a filter that takes a 2 different areas from the input texture, copy those pixels to a buffer, then write the buffer back to a selected area of the the output texture.

What I'm confused about is whether we should be using

a) a new texture for the temporary buffer b) a PBO with a renderbuffer c) a PBO with a colorbuffer

One way to do it would be to draw quads in the output and texture them with parts of the input. So lets say you have an input image that's 640x480 and your output is also 640x480 and you want to copy the area of the input that is from (25,25) to (50,50) to the output at, say, (100,100) and (200,200). You could do this (from memory, not tested) :

// ... Put the usual OpenGL setup here (see the FxFilter template for more info) ... // Copy from (25,25) in the input to (100,100) in the output glBegin (GL_QUADS); // Lower Left glTexCoord2f (25,25); glVertex2f (100,100);

// Lower Right glTexCoord2f (50,25); glVertex2f (125, 100);

// Upper Right glTexCoord2f (50, 50); glVertex2f (125, 125);

// Upper Left glTexCoord2f (25, 50); glVertex2f (100, 125); glEnd ();

// Copy from (25,25) in the input to (200, 200) in the output glBegin (GL_QUADS); // Lower Left glTexCoord2f (25,25); glVertex2f (200,200);

// Lower Right glTexCoord2f (50,25); glVertex2f (225, 200);

// Upper Right glTexCoord2f (50, 50); glVertex2f (225, 225);

// Upper Left glTexCoord2f (25, 50); glVertex2f (200, 225);

glEnd();

Does that help?

Darrin -- Darrin Cardani dcardani@apple.com

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