[plaything determination scratch children programming] ride a small motorcycle (dynamic background + camera control operation)

Preface

Blogger Homepage ： A Feng's homepage _CSDN
Programming tools ：scratch Web version
Resources related to this procedure ： Picture material and program source code

scratch It is a programming tool mainly for children , There are also many big friends like it , Because it does Simple and interesting , By building blocks , You can build some fun little programs .
This record is a Parkour （ Low profile version ） Mode games , however , We manipulate characters by facing the camera ！

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One . Program demonstration

The direction of the arrow in the upper right corner of the figure is the direction of the detected video motion , The number represents the range of motion ( The unit is the coordinate unit of the stage ）

Two . Dynamic background production

We only use a simple way here , To simulate the effect of dynamic background .

First , We need one The connection between the beginning and the end is natural Background image of .
The principle of dynamic background simulation is to place two pictures connected end to end in the stage ：

• One moves left from the center of the stage , Go to the far left of the stage
• One starts from the far right side of the stage , To the center of the stage

Once the picture moves to the specified position , Immediately return to the original position , Keep moving .

Implementation code ：
Because the stage cannot use sports building blocks , We implement the background image as a character

Be careful ： Why here x Used to judge coordinates Less than instead of be equal to ？ Because the smallest unit of background motion is 10, Probably There is no equal situation appear .

3、 ... and . Video detection and motion control

Building blocks	function
	Take the stage as the reference system , The distance the object moves in the video （ The unit is the stage coordinate unit ）
	Take the stage as the reference system , The direction of motion of the object in the video

In order to make the game a little more difficult , We can limit it only in A certain range of motion direction and distance To make the roles in the program react .

Implementation code ：

Four . obstacle —— Little stone

Simplicity , There is always only one small stone in our program , It is constantly from the stage Far right Moving to the stage Leftmost , Then return to the far right , You can simulate a kind of rock that constantly appears illusion .

Implementation code （ stone ）：

In order to make the game better , We can also let the little motorcycle emit when it meets a stone The alarm goes off .

Implementation code （ Lead ）：

how Fast and accurate Get the color of the character or background , I'm in another article Tips Mentioned in , You can click on the ： The cat walks in a maze

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Conclusion

🪐 Optimization assumption ：

1） You can use the variable module , add Health value and fraction attribute
2） Optimize the jumping action of the character , Simulate the effect of projectile motion , More beautiful

🪐 our “ Get on a scooter ” The program will be finished here ！ Some might wonder ： EH , The arrow in the upper right corner hasn't said yet ？ But arrows are not a major part of our program , Just to see the data collected by video detection more vividly .
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