Next, we discussed principles of animation, and applied some changes to regulate and smooth our motion. <\/p>\n\n\n\n
1. Normalized direction<\/h4>\n\n\n\n
Currently, our “direction” values create a vector of indeterminate length. Because we express our movement here as speed * direction<\/em>, we have implied that we only want Direction to contribute to the heading of the motion, not to have an effect on the velocity. To do this, we want to normalize<\/strong> our direction vector. Normalizing values let’s us bring them to a scale or standard. In terms of modifying our vector, the Normalize( )<\/strong> command will find the magnitude<\/strong> of a Vector3 (the distance from [0,0,0] to the point expressed by [x,y,z]) and divide all 3 vector values by that number, resulting in a Vector3 with a magnitude of 1.0.<\/p>\n\n\n\n This means that our scalar value speed<\/strong> will be the distance traveled (the magnitude of our motion vector) in each frame.<\/p>\n\n\n\n We made our ball appear to move smoothly, independent of our frame rate. Frame rate depends on the amount of time it takes to render a frame and execute all commands in between. As we saw in class, this rate can vary greatly from frame to frame. (To see this for yourself, click on the Stats<\/strong> button in the top bar of your Game<\/strong> window while the game is playing and look for the number next to “fps” (frames per second).<\/p>\n\n\n At first, we made our ball move a fixed amount in each frame (expressed as direction * speed<\/em>). In order to ensure that the ball appeared to move consistently over time rather than stutter, we introduced an additional multiplier – “delta time” – which returns the numeric value for seconds elapsed since the last frame was drawn. (This is generally a very low number – most games aim to run at 60 fps, leaving only 16.67ms between frames. ) By using “delta time”, we are incorporating the passage of time in the real world, and so a speed value of “2” now becomes “2 unit\/second” when multiplied by Time.deltaTime<\/a>.<\/p>\n\n\n\n Next, we created a paddle object, converted it into a prefab (by dragging it from our Hierarchy to our Assets folder) and placed prefab instances of the paddle on the left and right of the field of play, with x-values of -40 and 40.<\/p>\n\n\n\n We defined a new function MovePaddles( )<\/strong>, which we call from Update( )<\/strong> so that it runs every frame. We defined public variables for the GameObjects leftPaddle and rightPaddle (and associated them in the browser), and created a paddleSpeed value to control the motion. In the function definition, we made the following steps:<\/p>\n\n\n\n This creates the effect of moving the left and right paddle when we press the W, S, up arrow, and down arrow keys.<\/p>\n\n\n\n2. Smoothed motion<\/h4>\n\n\n\n
![\"\"](\"https:\/\/courses.ideate.cmu.edu\/53-353\/m2023\/wp-content\/uploads\/2022\/05\/image-2.png\")
<\/figure><\/div>\n\n\n3. Moving Paddles<\/h4>\n\n\n\n
\n
using System.Collections;\nusing System.Collections.Generic;\nusing UnityEngine;\n\npublic class Ping : MonoBehaviour\n{\n public GameObject myBall;\n public GameObject leftPaddle;\n public GameObject rightPaddle;\n\n public Vector3 direction;\n public float speed;\n\n public float paddleSpeed;\n\n \/\/ Start is called before the first frame update\n void Start()\n {\n myBall.transform.position = new Vector3(); \/\/ Reset the ball to 0,0,0\n\n \/\/ normalize the direction vector\n direction.Normalize();\n }\n\n \/\/ Update is called once per frame\n void Update()\n {\n \/\/ move the ball\n myBall.transform.position = myBall.transform.position + (direction * speed * Time.deltaTime);\n\n \/\/ move the paddles\n MovePaddles();\n\n }\n\n private void MovePaddles()\n {\n \/\/ get the current position of the paddles\n Vector3 leftPadPos = leftPaddle.transform.position;\n Vector3 rightPadPos = rightPaddle.transform.position;\n\n \/\/ adjust that position based on the keys pressed\n if (Input.GetKey(\"up\"))\n {\n rightPadPos.z = rightPadPos.z + (paddleSpeed * Time.deltaTime);\n }\n if (Input.GetKey(\"down\"))\n {\n rightPadPos.z = rightPadPos.z - (paddleSpeed * Time.deltaTime);\n }\n if (Input.GetKey(KeyCode.W))\n {\n leftPadPos.z += (paddleSpeed * Time.deltaTime);\n }\n if (Input.GetKey(KeyCode.S))\n {\n leftPadPos.z -= (paddleSpeed * Time.deltaTime);\n }\n\n\n \/\/ put the new position back into the object's transform\n rightPaddle.transform.position = rightPadPos;\n leftPaddle.transform.position = leftPadPos;\n\n }\n\n}\n<\/pre>\n","protected":false},"excerpt":{"rendered":"