Before we start, let me explain the thinking questions from the previous lesson. The key to the problem is that it is difficult to ensure that the trajectories of the front and rear frames are unified. In fact, if we think about it from another angle, the problem will become simpler. Aren't there 6 frames in total? We first move the blocks in the remaining 5 frames except the first frame to the same position, and then move the remaining 4 frames except the first two frames to the next position, and so on.
In terms of operation, it is actually to first select frames 2 to 6, move to the corresponding position, then hold down CTRL to subtract selected frame 2, move frames 3 to 6 to the next position, and then subtract selected frame 3... And so on until the position specification of frame 6 is completed. This is a very practical skill in operation. We will not describe the specific operations. If you have any questions, you can refer to the video tutorial of this lesson.
At present, our method of producing animation is still entirely manual, which is to produce it frame by frame. For example, when it comes to the movement of an object, we are involved in the setting of every frame from beginning to end. This method can bring maximum interventionability, but it also makes the production very cumbersome, especially when the number of frames is large. What we are going to learn today is to use frame transitions to create animations . The basic principle is to set the start frame and end frame of a certain movement, and then create an average transition between these two frames. If it is the movement of an object, the starting point frame and the end point frame of the movement are set first.
Create a new image, about 150×150, create a new layer and draw a square, moving it to the upper left corner. Then copy 1 frame, move the square to the lower right corner in the new frame, and set the layer transparency to 10%, roughly as shown in the left picture below. Then press the red arrow
button, the dialog box shown in the middle picture below will appear. The transition method at the red arrow refers to which frame the transition is relative to. Since we selected the second frame before, and there are only 2 frames in total, we can choose the default "Previous frame", you can also select "First frame". The number of frames to be added refers to the number of frames that will be occupied by the transition process. Here it is set to 3. Then plus the original 2 frames, the total of this animation will be 5 frames.
Since only one layer (the background layer has not changed) is participating in the animation, any of the layer options are now acceptable. But if you do not select the background layer, a transparent background will be formed. We will learn about the issue of animation background transparency in the future. Pay attention to the parameters at the green arrow, which include "position" and "opacity". The so-called parameters refer to the layer properties for animation transition. We have said before that the position and opacity of the layer can be animated, which is reflected here.
After confirmation, the effect you will see in the animation palette is roughly as shown in the figure below. You can clearly see that the position and opacity of the square have evenly transitioned. If the "Position" or "Opacity" parameters were turned off in the transition settings before, obviously there will be no current effect.
This method of making animation using transition method is relatively simple. We only need to consider the beginning and end of a certain animation, and the middle process will be completed automatically. In this case, the two frames at the beginning and end are called keyframes (KeyFrame), because they determine the shape of the transition. In the future we will also come into contact with animations with multiple keyframes.
Many cartoons today also use this key frame transition method. Although the pictures of cartoons are much more complicated, the basic principle is the same. However, due to the characteristics of uniform transition, sometimes the picture is not vivid enough and lacks expressiveness. This is a limitation of Photoshop functionality.
Now we are facing a new topic, which is how to make the animation play in a perfect loop, that is, from A to B and back to A. Only in this way can a complete cycle be formed, which is called a reciprocating animation. For our current animation, the "going back" process can be accomplished by copying and moving frames. First, copy frame 4. After copying, frame 4 and frame 5 have the same content, and the original frame 5 becomes frame 6. Then manually move frame 5 to the back of frame 6, thus swapping the order of the two. The process is shown in the figure below. It can be seen from this operation that the copied frames do not all appear at the end, but appear behind the original frames. This feature should be noted.
Follow this method to copy frame 3 to frame 7 and frame 2 to frame 8. It is not necessary to copy frame 1 to frame 9, because frame 9 will be frame 1 again after playing, and the contents of the two are the same. It actually plays the same frame twice as long.
When the undo operation reaches only 5 frames, now we introduce another simple method, that is, select frame 5 and then execute the frame transition again, and set the transition mode to "First Frame", which means starting from the current frame (frame 5) ) to transition to frame 1, just keep the number of added frames at 3, or you can set a larger value. After confirmation, you will get a reciprocating animation. The picture below shows the effect of adding 7 frames.
When playing this reciprocating animation, you will find a problem, that is, the block takes a long time to "return". This is of course because we use more frames for the same distance. If the delay from frame 6 to frame 12 is set to 0.05, it will be almost the same as before.
You may have a question, that is, since the overall time is almost the same, why is it necessary to set a 7-frame transition? Wouldn't 3 frames be enough as before? This involves an issue of animation precision. As an animation that expresses motion, the more frames it has, the more moments it can express, the smaller the difference between frames, and the smoother the overall effect of the transition. Of course, it will also bring some inconvenience in production and storage. Therefore, generally speaking, it is not appropriate to set a large number of frames, as long as it meets the viewing needs.
This problem also exists in video production, and the principle is the same. We have said that the number of frames per second in a movie is 24, so if you use a high-speed camera to shoot a movie at 48FPS and then play it back at the usual 24FPS, what we will see is a picture that is twice as slow as the normal motion speed. This is how slow motion in action movies is created.
If a film shot with an ordinary camera wants to achieve slow motion, it is necessary to extend the dwell time of each frame. To achieve the effect of being twice as slow, the delay of each frame must be adjusted from 1/24 to 1/12, so that actually every frame Only 12 frames are broadcast per second, and the picture will have a more obvious beating feeling. So the real slow motion is not "arrange normally, play slowly", but "shoot fast, play normally".
In the same way, low-speed photography means shooting at a very low frame rate and then playing it back normally to create a fast-forward effect. It is often used to shoot scenes that require a long wait and then quickly present them to the audience, such as flowers blooming, sunset, etc.
What you need to master in this lesson is the method of using frame transition to create animations and the concept of key frames. When using it, pay attention to the options of the transition method. You need to figure out whether it is the "previous frame" or the "first frame". Generally speaking, after The field is used to create "return fields" to form reciprocating animations. In the future, the animations produced by everyone should give priority to the reciprocating method to form a more perfect loop effect.
In the next section we introduce the design thinking of animation.