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Help => Graphics => Topic started by: smurf on November 19, 2024, 04:40:51 pm

Title: Drawing a subset of a vertex array?
Post by: smurf on November 19, 2024, 04:40:51 pm

I have a particle system where sparks burn out over time.
Instead of creating a brand new VertexArray every frame with the burnt-out particles removed, I wanted to re-use the same VertexArray and just shift things around so that the burnt-out ones are on the end, and then not draw them by passing a count parameter to the Draw function. The idea is by not creating a new VertexArray every frame this should be much more performant.

But it seems the window.Draw function does not quite give me the overload I need.

renderWindow.Draw(vertexArray, 0, vertexCount, vertexArray.PrimitiveType);

This is invalid code because the first parameter needs to be an array of vertices instead of a vertexArray  ::)

but the VertexArray class does not expose its internal array of vertices. So any way I can do this?

Title: Re: Drawing a subset of a vertex array?
Post by: fallahn on November 20, 2024, 10:52:17 am

You can use the [] operator (https://www.sfml-dev.org/documentation/2.6.2/classsf_1_1VertexArray.php#a913953848726c1c65f8617497e8fccd6) of VertexArray

window.draw(&vertices[offset], count, sf::Triangles);
 

Title: Re: Drawing a subset of a vertex array?
Post by: smurf on November 20, 2024, 03:04:29 pm

Thanks!

But I'm using SFML.Net and it doesn't seem to have that in C# :(

Title: Re: Drawing a subset of a vertex array?
Post by: eXpl0it3r on November 24, 2024, 01:36:09 pm

Unfortunately, SFML.Net doesn't offer anything like that, but you can use LINQ to Skip() to the wanted position.