As the old saying goes: it's hard to buy an inch of time. But at least in blender's world, we can still use a wealth of means to "control" the flow of time, the theme of this issue is to use the geometric node function to make a clock dial that can move at the real time flow rate, let's see how to design it!
Step 1: Make the dial and hands
Since you want to do a clock, then naturally first have to make the most basic look, we can use the column to achieve the dial, and then in the center of the column to do a "load" hands of the reel, the style of the dial we can refer to the photos or their own clocks searched on the Internet, you can play freely, and then put 1 to 12 o'clock numbers in various positions, such as Figure 1, a basic dial is done.
Next we do the hands, the hands of the clock are representing the hours, minutes, seconds of the short, medium, long needles, we can first use the plane to adjust the shape of the three hands, remember to be sure to put the origin of the three hands are placed in the center of the dial, so that there will be no problems when rotating, the specific design can refer to Figure 2. This way, our dial design is complete, and it's time for the geometry nodes to appear.
Step 2: Use geometry nodes to calculate the angle of pointer rotation
At this point you may feel very nonsensical, pointer rotation why not directly by adding a drive to the rotation property? Indeed, this method can directly achieve the effect of pointer rotation, but there is a major disadvantage: it requires three different drives to achieve, and the drives are independent of each other, can not be controlled by a parameter at the same time, and the fine-tuning of the drive is more troublesome, such as you want time acceleration, deceleration, reversal, need to adjust many times, very troublesome, as a lazy person, through the geometry node to control can be said to be once and for all, worth careful study.
First of all, we can't directly use these three pointers to make geometric nodes, so we have to first create a new object, put it in the center of the dial, and then add geometric node functions to it, put the hour hand, minute hand, second hand into the node editor, through the transformation, merge geometry to achieve the simultaneous output of the three pointers, at this time you may need to use the "transformation" to properly adjust the position of the three pointers, so as not to overlap, specifically set the reference figure 3.
The next step is the point, how do we rotate through a value, let the three hands turn a circle by the second hand, the minute hand goes 1/60 turn, the minute hand goes 1/60, the minute hand goes 1/12 turns? In fact, this logic is very familiar to everyone, so we only need to use mathematical nodes to connect them.
First of all, because our clock is face up, that is, placed along the Z axis, so the pointer also has to rotate along the Z axis to be correct, so we need to use "merge XYZ" so that the value can control the rotation Z alone, but note that in the "transform", the rotation value uses the degrees we are accustomed to, and once the "merge XYZ" is connected, it is converted to the mathematical form 180° is equal to a π, that is, the pointer rotates for one week equals 2π.
Based on this premise, we can correctly design the pointer rotation, starting from the most basic seconds hand, in blender 3.1 version of the geometry node added a "scene time" function, it provides the most basic unit of time "seconds", if you use version 3.0, you need to use the "value" to make a drive, such as setting the video frame rate of 30p, we need "#frame/30" as "seconds".
We multiply the "seconds" by a π, which is equivalent to letting the pointer go half a circle in one second, and if it wants to operate according to the real time flow rate, it needs to be divided by another 30, at which time the second hand will work correctly, of course, it may also need to be followed by a multiplication of -1 to make him rotate clockwise, it is recommended to put these nodes in a box, it will be more convenient to adjust, specific settings refer to Figure 4.
After getting the real time flow rate of one second, we only need to divide it by 60 and connect it to the minute hand, so that we can achieve the purpose of turning the second hand once, turning the minute hand by 1/60 lap, and then dividing the speed of the minute hand by 12, connecting it to the hour hand, turning the minute hand once, and the hour hand going 1/12 lap is natural.
At this time, if we want to adjust the speed of the pointer, steering and the starting position of the 1st frame, we only need to add a "multiplication and then add" after the "second" box we got before, the multiplier at this time is to control the overall speed and steering, the larger the multiplier, the faster the rotation, the multiplier is negative, and the addition is rotated counterclockwise, and the addition is here to adjust the starting position, such as you want the 1st frame at 8 o'clock, you can adjust by adding, more convenient, at this time you can connect these two values to the "group input", In this way, even if you do not enter the geometry node, you can directly adjust it in the modifier interface, which is simple and intuitive.
A comprehensive overview of the Geometry Node Editor used in this article
Summary of this chapter: Geometry nodes can achieve many effects quickly
In fact, we have emphasized the strength of geometric nodes in the last issue, although a certain amount of mathematical logic thinking ability is required, but once it is integrated, it can quickly and efficiently achieve a lot of previous needs to adjust a lot of parameters, and even may have a lot of wrong effects, so in the future for a period of time, geometric nodes will be the main goal of our teaching, this "programming thinking" in 3D design is of great importance, we must master.