Question: My laptop has a nice GPU with dedicated video RAM. But I've noticed while playing Minecraft that the computer doesn't seem to be *using* it for anything. Only about 100 MB get used at all according to the Windows Task Manager, while it eats up about half my regular RAM.

I had thought that VRAM would be used for storing models and textures and stuff, which would reduce the demand on regular RAM; if that's true, the textures and models must be far smaller than I'd thought. (note that this is a heavily modded install, with much more complex models and textures than your standard Minecraft.)

If it's not true, what *is* VRAM used for? Is there any way I can get my computer to make better use of it?

Answer: 
Video RAM is specifically designed to store anything that is necessary to render a frame of video. When gaming, this includes textures, models, and other graphics-specific data like shader information and lighting maps. Generally, none of this data is stored in main system RAM as you alluded to, although VRAM is not specifically designed to reduce demand on regular RAM.

Minecraft is a bit of a different beast than most games. I'd assume you're playing the Java version for PC. Java is a (relatively) high-level programming language compared to others such as C or C++ which other games will commonly be written in. Because of this, Java is inherently at a disadvantage when it comes to memory usage requirements. This is why your main system memory takes such a huge hit when running Minecraft, a very resource-intensive program written in Java.

I'm not surprised that your video RAM usage is low, though - and truthfully neither should you. As it is only meant to store textures and models, and Minecraft is, well, a game based on cubes and 16x16 textures, I think you can realize why your VRAM usage is so low.
> 
> It's not about poor coding.
> 
> 
> 

I would like to point something out. Modern graphics cards *could* process a large part of Minecraft in the card itself. Systems like PhysX attempt to do just that—CUDA, OpenCL etc. Consequently, this would increase VRAM usage.

Here's some things that could easily (relatively speaking) be offloaded to the graphics driver:

* Tick updates of blocks (think leaf blocks dying, lighting updates, etc.)
* Procedural generation
* Fluid updates
* Redstone
* Physics

However, GPU processing in a shader language (GLSL, HLSL, SPIR-V) is much more difficult and bug prone than a high level language like Java. Thus, all of these things are performed on the CPU.

Although several games have implemented some of that in GPUs before, Minecraft didn't have the large, skilled resource pool that triple-A titles have.

---

### The Math

Suppose Minecraft uses a 32-bit color scheme.

```
32 bits per color
4 colors per pixel (red, green, blue, alpha)
8 bits per byte
(32 bits * 4 colors per pixel) / 8 bits per byte = 128 / 8 = 16 bytes per pixel.

```

```
100MB / 16 bytes per pixel = 6,250,000 pixels
sqrt(6250000) = 2500x2500 image resource in GPU (uncompressed)
2500 pixels wide|tall / 16 pixels wide|tall = 156.25 tiles wide|tall (assuming 16x16 tile size)
156.25 tiles wide * 156.25 tiles tall = ~24,414 16x16 tiles.

```

In summary, you can store ~24,414, 16x16 tiles in an uncompressed, 32-bit, image resource in VRAM.

This exercise really helped me wrap my head around why [Factorio had issues with it's sprite-sheets](https://gamedev.stackexchange.com/questions/73316/how-do-we-solve-big-video-memory-requirements-in-a-2d-game)