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What is instancing OpenGL?
Instancing is a technique where we draw many (equal mesh data) objects at once with a single render call, saving us all the CPU -> GPU communications each time we need to render an object.
How does gpu instancing work?
GPU Instancing only renders identical Meshes with each draw call, but each instance can have different parameters (for example, color or scale) to add variation and reduce the appearance of repetition. GPU Instancing can reduce the number of draw calls used per Scene.
What is vertices in OpenGL?
A Vertex Array Object (VAO) is an OpenGL Object that stores all of the state needed to supply vertex data (with one minor exception noted below). It stores the format of the vertex data as well as the Buffer Objects (see below) providing the vertex data arrays.
What does instancing mean in particles OpenGL?
“Instancing” means that we have a base mesh (in our case, a simple quad of 2 triangles), but many instances of this quad. Technically, it’s done via several buffers : Some of them describe the particularities of each instance of the base mesh. You have many, many options on what to put in each buffer.
What makes the last line of OpenGL interesting?
What makes this code interesting is the last line where we call glVertexAttribDivisor. This function tells OpenGL when to update the content of a vertex attribute to the next element. Its first parameter is the vertex attribute in question and the second parameter the attribute divisor.
Is it bad to draw two quads at once in OpenGL?
This is a very bad idea, because this means that all your shiny GTX’ 512+ multiprocessors will all be dedicated to draw ONE quad (obviously, only one will be used, so that’s 99% efficiency loss). Then you will draw the second billboard, and it will be the same.
What’s the difference between particles and gldrawarrays in OpenGL?
The difference comes when rendering. Instead of using glDrawArrays (or glDrawElements if your base mesh has an index buffer), you use glDrawArrraysInstanced / glDrawElementsInstanced, which is equivalent to calling glDrawArrays N times (N is the last parameter, in our case ParticlesCount) : Bue something is missing here.