float f3 = MathHelper.lerp(partialTicks, playerEntityIn.prevRenderArmPitch, playerEntityIn.renderArmPitch);
float f4 = MathHelper.lerp(partialTicks, playerEntityIn.prevRenderArmYaw, playerEntityIn.renderArmYaw);
matrixStackIn.rotate(Vector3f.XP.rotationDegrees((playerEntityIn.getPitch(partialTicks) - f3) * 0.1F));
matrixStackIn.rotate(Vector3f.YP.rotationDegrees((playerEntityIn.getYaw(partialTicks) - f4) * 0.1F));