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Author Topic: One draw-call for all 2dStuff ..  (Read 4044 times)

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HeinzK

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One draw-call for all 2dStuff ..
« on: August 21, 2017, 03:43:28 pm »
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« Last Edit: December 04, 2019, 08:32:40 am by HeinzK »
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eXpl0it3r

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Re: One draw-call for all 2dStuff ..
« Reply #1 on: August 21, 2017, 04:11:34 pm »
Btw. we have [code=cpp][/code] for when posting code. ;)

Not sure what's your point here exactly.
If you use a vertex array of a certain primitive type, you can easily batch all the vertices together, no need for SFML to do anything.
If you have multiple different primitive types, you have to run multiple draw calls. That doesn't just go away by changing the interface, as it also requires multiple draw calls in OpenGL.

And if you just look for a vertex array struct thingy, then well we have that sf::VertexArray, but often you'll want to use your own custom thing, when you want direct access to the vector of vertices.
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eXpl0it3r

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Re: One draw-call for all 2dStuff ..
« Reply #2 on: August 21, 2017, 04:58:47 pm »
There's no point in doing this. It would only add an unnecessary function to the API and otherwise have no advantage. You can draw all your objects simply like this:

std::vector<sf::Drawable*> drawables;
for(auto drawable : drawables) {
    window.draw(&drawable);
}

or for vertex arrays

struct VertexArray {
    std::vector<sf::Vertex> vertices;
    sf::PrimitiveType primitive_type;
}

std::vector<VertexArray> collection;

for(auto& vertex_array : collection) {
    window.draw(vertex_array.vertices.data(), vertex_array.vertices.size(), vertex_array.primitive_type);
}
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eXpl0it3r

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Re: One draw-call for all 2dStuff ..
« Reply #3 on: August 21, 2017, 05:38:17 pm »
As I mentioned.

If you use a vertex array of a certain primitive type, you can easily batch all the vertices together, no need for SFML to do anything.

If you have multiple different primitive types, you have to run multiple draw calls. That doesn't just go away by changing the interface, as it also requires multiple draw calls in OpenGL.
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eXpl0it3r

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Re: One draw-call for all 2dStuff ..
« Reply #4 on: August 22, 2017, 12:39:50 pm »
Why should Vtx be an address?
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eXpl0it3r

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Re: One draw-call for all 2dStuff ..
« Reply #5 on: August 22, 2017, 04:18:06 pm »
sf::Vertex Vtx = pVertices->front();
This creates a copy of a single vertex stored in k_PolyLines. So it's not only a completely different object, but it's not connected in any way to the vector and thus you can't use it for the draw call.
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