and its content will be passed to the fragment shader. A variable that you can fill with a value from this shader, A vertex shader may contain : // A variable that receives a value passed by the actual program In GLSL, attributes and varyings are special variables you declare in your scripts. You can also generate new data that will then be passed from the vertex shader to the fragment shader input, these are special variables called varyings.

You can for example have, for each vertex in the scene, an integer variable indicating to which object or entity this vertex belongs to, and use it in your vertex shader code. Passing data from shader to shaderĪttributes are special data that is passed to the GPU for each vertex and that you can use within a shader. It takes pixel coordinates as well as data calculated from the previous stages (vertex shader) and returns a color for each pixel. The fragment shader is the last shader executed during rendering, and is the one generating the image to be put on the screen. This is where you can implement transformations and displace vertices of a mesh for some effects. The vertex shader is the first shader executed during the rendering, it takes vertices of the scene and attributes as inputs, and outputs new vertices. In Minecraft shaderpacks, they have respectively the extensions.

The two 'main' shaders that are executed during rendering are the vertex shader and the fragment shader (sometimes called the pixel shader). Vertex and fragment shadersĪs stated previously, there are several types of shader. I'll anyway try to give a brief summary about shaders and how they can 'know' details about the scene (positions, entities.), more than just pixel colors. Here is also a page listing detailed resources about shader programming and Optifine's pipeline : īe sure to check it as you can probably find most of the information you are looking for here. Thus each programmable rendering stage has its own shader whose inputs and outputs depend on the stage : įor Minecraft, you can find some information about the shader layout on the wiki : For some of these stages you can implement a custom shader program.

The rendering process, called the rendering pipeline, is executed by the GPU and is split in several stages. I don't know what is your knowledge of shaders, so I'll walk through several concepts relevant for your question. Describing a shader as something that 'gets a set of pixels as an input and returns a bunch of new pixels' is a bit of an oversimplification.

Minecraft with shaders