Sturmlilie

Apitrace tutorial

Debugging OpenGL issues in Minecraft mods using apitrace

In the transition of Minecraft version 1.14 to 1.15, Mojang introduced some sweeping changes to the way rendering is performed; while the internal code still relies on GL1-era immediate-mode, block and entity renderer classes now provide their vertices to a specific RenderLayer* which are later rendered in ordered batches.

These changes broke a majority of Minecraft mods; in the process of porting a mod to 1.15, I had to frequently rely on a tool called “apitrace”, and I thought a quick how-to might come in handy for others struggling with similar problems. Apitrace allows capturing every OpenGL call an application makes, and later replaying these calls and inspecting the entire GL state machine at each rendering step.

For this tutorial, I am using the MultiMC launcher.

First step: Install apitrace

apangin

_hashCode                               java/lang/Object.hashCode()I
_getClass                               java/lang/Object.getClass()Ljava/lang/Class;
_clone                                  java/lang/Object.clone()Ljava/lang/Object;
_dabs                                   java/lang/Math.abs(D)D
_dsin                                   java/lang/Math.sin(D)D
_dcos                                   java/lang/Math.cos(D)D
_dtan                                   java/lang/Math.tan(D)D
_datan2                                 java/lang/Math.atan2(DD)D
_dsqrt                                  java/lang/Math.sqrt(D)D
_dlog                                   java/lang/Math.log(D)D

KdotJPG

/**
 * K.jpg's OpenSimplex 2, smooth variant ("SuperSimplex")
 *
 * More language ports, as well as legacy 2014 OpenSimplex, can be found here:
 * https://github.com/KdotJPG/OpenSimplex2
 */

public class OpenSimplex2S {

    private static final long PRIME_X = 0x5205402B9270C86FL;