[SOLVED] Best approach for rendering footprints

[Martin Sand]

I am currently working on an implementation for footprints etc.

To get this working I have created a struct which I keep in a vector and let it render every frame.
Since the texture does not change but is kept in the GPU memory, I assume it is quite fast although the game will produce thousands of footprints during a level. Every footprint is 1 sprite.

int vectorsize = m_Tracks.size();
for(int iterator = 0; iterator < vectorsize; ++iterator;){
  m_Window.draw(m_Tracks[iterator]->getComponent<RenderComponent>()->getSprite());
}

What is the best optimization (rendering time) for this?

• Create an image and add the footprint every frame (direct manipulation of the pixel via getPixel, setPixel) and apply the image to the render texture of 1 sprite?
• Use a texturerender instead of direct pixel manipulation?
• Keep the current implementation and optimize to only render sprites in current view rect?

I coudl not find any good result in the forum search.

Best regards
Martin

[Laurent]

Use a single vertex array with all the footprints inside.

[Martin Sand]

Perfect, did the job 

I measured the difference. By design my m_Tracks vector was faster than the VertexArray when it was below ~ 3k sprites. The VertexArray always stayed at the constant render time (at least what I measured through sf::Clock in microseconds). The vector was getting slower and slower beyond 3k sprites (sprite is 21x3 px).