What is overdraw?

[Ezio Auditore]

If possible please give explanations with reasons (I mean graphical overdraw)

[AdamBGames]

1 minute ago, Ezio Auditore said:

If possible please give explanations with reasons

I believe this is when a GPU starts to take more power from the PCIe lane or power cables than its suppost to, this can be bad for the motherboard if it is the PCIe slot but with the constant checks GPUs go through during production this isnt a big problem

[iRileyx]

Commonly described in graphics technical terms as the process by which during the rendering of a scene, a pixel at a given X,Y location in the final image is replaced by one which is closer to the view point than the existing pixel as determined by their corresponding Z values. - Wiktionary.

Or do you mean power overdraw?

[Ezio Auditore]

Just now, RKRiley said:

Commonly described in graphics technical terms as the process by which during the rendering of a scene, a pixel at a given X,Y location in the final image is replaced by one which is closer to the view point than the existing pixel as determined by their corresponding Z values. - Wiktionary.

Or do you mean power overdraw?

No I mean the earlier one and I had read that wikitionary link, could you please explain it?

[Zodiark1593]

2 hours ago, Ezio Auditore said:

No I mean the earlier one and I had read that wikitionary link, could you please explain it?

Overdraw means writing to a given pixel more than once per frame. If you've a transparent window in front of an object, that object will incur writes to the pixels it covers, and the glass will write to pixels that it covers, typically from a back to front order. Opaque objects such as smoke tend to incur heavy overdraw as well. 

 

Overdraw is significant in that writing to many pixels more than once eats into fillrate, and more significantly, bandwidth. In addition, shaders are applied both the pixels composing the transparent object, and the object behind, potentially incurring a heavy compute cost as well. 

 

Culling techniques drastically reduce overdraw from solid, static objects.