[1.16.5] Drawing lines from the center of screen with View Bobbing enabled

[Zergatul]

It is simple task when View Bobbing is disabled. In RenderWorldLastEvent I do this:

Vector3d view = Minecraft.getInstance().gameRenderer.getMainCamera().getPosition();

MatrixStack stack = event.getMatrixStack();
stack.translate(-view.x, -view.y, -view.z);

GL11.glPushMatrix();
RenderSystem.multMatrix(stack.last().pose());

double centerX = view.x;
double centerY = view.y;
double centerZ = view.z;

double drawBeforeCameraDist = 1;
double pitch = (mc.player.xRot) * Math.PI / 180;
double yaw = (mc.player.yRot) * Math.PI / 180;

centerX -= Math.sin(yaw) * Math.cos(pitch) * drawBeforeCameraDist;
centerZ += Math.cos(yaw) * Math.cos(pitch) * drawBeforeCameraDist;
centerY -= Math.sin(pitch) * drawBeforeCameraDist;

But when I enabled View Bobbing, the center point starts moving in half-circle trajectory. I looked into GameRenderer class, bobView method. It calculates few float values and applies them to MatrixStack. I don't know if I can use this matrix (it comes in RenderWorldLastEvent), so I copied code from bobView and started experimentation. This is the best I can get:

// omitted same lines from my first example

double centerX = view.x;
double centerY = view.y;
double centerZ = view.z;

double deltaXRot = 0;
double deltaZRot = 0;
double translateX = 0;
double translateY = 0;

if (mc.options.bobView && mc.getCameraEntity() instanceof PlayerEntity) {
    PlayerEntity playerentity = (PlayerEntity)mc.getCameraEntity();
    float f = playerentity.walkDist - playerentity.walkDistO;
    float f1 = -(playerentity.walkDist + f * event.getPartialTicks());
    float f2 = MathHelper.lerp(event.getPartialTicks(), playerentity.oBob, playerentity.bob);
    translateX = (double)(MathHelper.sin(f1 * (float)Math.PI) * f2 * 0.5F);
    translateY = (double)(-Math.abs(MathHelper.cos(f1 * (float)Math.PI) * f2));
    deltaZRot = MathHelper.sin(f1 * (float)Math.PI) * f2 * 3.0F;
    deltaXRot = Math.abs(MathHelper.cos(f1 * (float)Math.PI - 0.2F) * f2) * 5.0F;
}

double drawBeforeCameraDist = 1;
double yaw = (mc.player.yRot) * Math.PI / 180;
double pitch = (mc.player.xRot + deltaXRot) * Math.PI / 180;

centerY -= translateY;
centerX += translateX * Math.cos(yaw);
centerZ += translateX * Math.sin(yaw);

centerX -= Math.sin(yaw) * Math.cos(pitch) * drawBeforeCameraDist;
centerZ += Math.cos(yaw) * Math.cos(pitch) * drawBeforeCameraDist;
centerY -= Math.sin(pitch) * drawBeforeCameraDist;

Now center point doesn't jump to the right and left on the screen. And it doesn't jump up and down, but only if I look straight forward. As pitch angle goes far from 0 (either to -90 or 90), center point jumps harder up and down. Is my approach right? Or should I learn about MatrixStack and try to use it?