CODEWITHSUNDEEP
copengloptimization
badcc
badcc

Reputation: 232

glDrawArrays with multiple triangles in a single array with a persistent first and count

I have a bunch of polygon data that I want to draw. I pulled out that drawing code so that it currently looks like this

for (int Index = 0; Index < Count; Index++) {
    glDrawArrays(GL_TRIANGLE_FAN, Index * 4, 4);
}

I have a giant one dimensional array filled with multiple triangles, a new triangle every 4 vertices. Are there any OpenGL functions that I can replace this entire loop with so that I don't have the overhead of each glDrawArrays call? glMultiDrawArrays is sort of what I want, except I don't need a different first (well, I need a different first, but multiplied by a constant) and count each time.

I thought something like glVertexAttribDivisor would work, but nothing was drawing after I added it, I'm not completely sure if it works without instancing either.

EDIT: I am using a triangle fan, and I am buffering the vertices every frame.

Upvotes: 3

Views: 1514

Answers (1)

genpfault
genpfault

Reputation: 52082

glDrawElements() + GL_PRIMITIVE_RESTART & glPrimitiveRestartIndex().

Upvotes: 2

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