导读：
1.Moving Dot Grid Demo: 让点状网格在屏幕上呈正弦式向左或向右移动
注：关键在于点坐标的设置，可以将时间看做变量，使用sin函数，然后每帧都刷新，即可获得动态效果
% Use the meshgrid command to create our base dot coordinates 获得网格点坐标 dim = 10; [x, y] = meshgrid(-dim:1:dim, -dim:1:dim); % Scale this by the distance in pixels we want between each dot 调整坐标尺度 pixelScale = screenYpixels / (dim * 2 + 2); x = x .* pixelScale; y = y.* pixelScale; % Calculate the number of dots 计算点的数量 numDots = numel(x); % Make the matrix of positions for the dots into two vectors 获取点的坐标向量 xPosVector = reshape(x, 1, numDots); yPosVector = reshape(y, 1, numDots); % We can define a center for the dot coordinates to be relaitive to. Here 设置中心 % we set the centre to be the centre of the screen dotCenter = [screenXpixels / 2 screenYpixels / 2]; % Set the color of our dot to be random 设置颜色 dotColors = rand(3, numDots); % Set the size of the dots randomly between 10 and 30 pixels 设置点的大小为10-30之间 dotSizes = rand(1, numDots) .* 20 + 10; % Our grid will oscilate with a sine wave function to the left and right 设置正弦函数的参数 % of the screen. These are the parameters for the sine wave % See: http://en.wikipedia.org/wiki/Sine_wave amplitude = screenYpixels * 0.25; 波幅 frequency = 0.2; 频率 angFreq = 2 * pi * frequency; 角频率 startPhase = 0; 初始相位 time = 0; 时间 % Sync us and get a time stamp 获取时间戳 vbl = Screen(‘Flip‘, window); waitframes = 1; % Maximum priority level 设置优先级 topPriorityLevel = MaxPriority(window); Priority(topPriorityLevel); % Loop the animation until a key is pressed 循环 while ~KbCheck % Position of the square on this frame 某一帧上的位置 gridPos = amplitude * sin(angFreq * time + startPhase); % Draw all of our dots to the screen in a single line of code adding 绘制 % the sine oscilation to the X coordinates of the dots Screen(‘DrawDots‘, window, [xPosVector + gridPos; yPosVector],... dotSizes, dotColors, dotCenter, 2); % Flip to the screen vbl = Screen(‘Flip‘, window, vbl + (waitframes - 0.5) * ifi); % Increment the time time = time + ifi; end
2.Scaled Dot Grid Demo:如何扩展和收缩绘制在屏幕上的点网格。点的大小也随之调节
注：大体思路与第一个示例一致。主要是将点的坐标和点的大小设置为与时间相关的函数
% Use the meshgrid command to create our base dot coordinates dim = 10; [x, y] = meshgrid(-dim:1:dim, -dim:1:dim); % Scale this by the distance in pixels we want between each dot pixelScale = screenYpixels / (dim * 2 + 2); x = x .* pixelScale; y = y.* pixelScale; % Calculate the number of dots numDots = numel(x); % Make the matrix of positions for the dots into two vectors xPosVector = reshape(x, 1, numDots); yPosVector = reshape(y, 1, numDots); % We can define a center for the dot coordinates to be relaitive to. Here % we set the centre to be the centre of the screen dotCenter = [screenXpixels / 2 screenYpixels / 2]; % Set the color of our dot to be random dotColors = rand(3, numDots); % Set the maximum size of the dots to 25 pixels 设置点最大为25pixel maxDotSize = 25; % Our grid will pulse by taking the absolute value of a sine wave, we % therefore set the amplitude of the sine wave to 1 as this will be a % multiplicative scale factor ranging between 0 and 1. % With 0 the dots will all be on top of one another. With 1 the gird will % have its maximum size. % These are the parameters for the sine wave % See: http://en.wikipedia.org/wiki/Sine_wave amplitude = 1; frequency = 0.05; angFreq = 2 * pi * frequency; startPhase = 0; time = 0; % Sync us and get a time stamp vbl = Screen(‘Flip‘, window); waitframes = 1; % Maximum priority level topPriorityLevel = MaxPriority(window); Priority(topPriorityLevel); % Loop the animation until a key is pressed while ~KbCheck % Scale the grid coordinates 调整网格坐标,这里使用了绝对值函数 scaleFactor = abs(amplitude * sin(angFreq * time + startPhase)); % Scale the dot size. Here we limit the minimum dot size to one pixel 调整点的大小(1~25)，这里用最大值函数 % by using the max function as PTB won‘t allow the dot size to scale to % zero (sensibly, as you‘d be drawing no dots at all) thisDotSize = max(1, maxDotSize .* scaleFactor); % Draw all of our dots to the screen in a single line of code adding % the sine oscilation to the X coordinates of the dots Screen(‘DrawDots‘, window, [xPosVector; yPosVector] .* scaleFactor,... thisDotSize, dotColors, dotCenter, 2); % Flip to the screen vbl = Screen(‘Flip‘, window, vbl + (waitframes - 0.5) * ifi); % Increment the time time = time + ifi; end
3.Moving Square Demo:使一个正方形在屏幕上呈正弦向左或向右移动
注：大体思路和第一个示例一致，只是将目标换成了矩形
% Make a base Rect of 200 by 200 pixels baseRect = [0 0 200 200]; % Set the color of the rect to red rectColor = [1 0 0]; % Our square will oscilate with a sine wave function to the left and right % of the screen. These are the parameters for the sine wave % See: http://en.wikipedia.org/wiki/Sine_wave amplitude = screenXpixels * 0.25; frequency = 0.2; angFreq = 2 * pi * frequency; startPhase = 0; time = 0; % Sync us and get a time stamp vbl = Screen(‘Flip‘, window); waitframes = 1; % Maximum priority level topPriorityLevel = MaxPriority(window); Priority(topPriorityLevel); % Loop the animation until a key is pressed while ~KbCheck % Position of the square on this frame 每一帧上方形各点的x坐标变化量 xpos = amplitude * sin(angFreq * time + startPhase); % Add this position to the screen center coordinate. This is the point 调整到以屏幕中心点为中心 % we want our square to oscillate around squareXpos = xCenter + xpos; % Center the rectangle on the centre of the screen centeredRect = CenterRectOnPointd(baseRect, squareXpos, yCenter); % Draw the rect to the screen Screen(‘FillRect‘, window, rectColor, centeredRect); % Flip to the screen vbl = Screen(‘Flip‘, window, vbl + (waitframes - 0.5) * ifi); % Increment the time time = time + ifi; end
4.Multiple Moving Squares Demo: 使两个正方形在屏幕上以正弦方式移动，具有不同的颜色和不同的横向偏移
注：和示例三的思路一致，只是多加了一个矩形。
% Make a base Rect of 200 by 200 pixels baseRect = [0 0 200 200]; % Set the color of the top rect to red and the bottom blue topColor = [1 0 0]; bottomColor = [0 0 1]; % Our square will oscilate with a sine wave function to the left and right % of the screen. These are the parameters for the sine wave % See: http://en.wikipedia.org/wiki/Sine_wave amplitude = screenXpixels * 0.25; frequency = 0.2; angFreq = 2 * pi * frequency; time = 0; % Our two squares will be pi out of phase 初始位置反相 startPhaseOne = 0; startPhaseTwo = pi; % Sync us and get a time stamp vbl = Screen(‘Flip‘, window); waitframes = 1; % Maximum priority level topPriorityLevel = MaxPriority(window); Priority(topPriorityLevel); % Loop the animation until a key is pressed while ~KbCheck % Position of the two squares on this frame 每一帧中心点位置变化量 xposOne = amplitude * sin(angFreq * time + startPhaseOne); xposTwo = amplitude * sin(angFreq * time + startPhaseTwo); % Add this position to the screen center coordinate. This is the point 矩形中心点的横坐标 % we want our squares to oscillate around squareXposOne = xCenter + xposOne; squareXposTwo = xCenter + xposTwo; % Center the rectangle on the centre of the screen 获取矩形每帧的坐标 centeredRectOne = CenterRectOnPointd(baseRect, squareXposOne,... screenYpixels * 0.25); centeredRectTwo = CenterRectOnPointd(baseRect, squareXposTwo,... screenYpixels * 0.75); % Draw the rect to the screen Screen(‘FillRect‘, window, [topColor‘ bottomColor‘],... [centeredRectOne‘ centeredRectTwo‘]); % Flip to the screen vbl = Screen(‘Flip‘, window, vbl + (waitframes - 0.5) * ifi); % Increment the time time = time + ifi; end
5.Moving Colour Change Square Demo: 使一个正方形在屏幕上呈正弦运动，其颜色根据其屏幕位置而动态变化
注：在此demo中，矩形是在红蓝两个色调之间做正弦变换。在示例3的基础上，进一步做颜色的变化
% Make a base Rect of 200 by 200 pixels baseRect = [0 0 200 200]; % Our square will oscilate with a sine wave function to the left and right % of the screen. These are the parameters for the sine wave % See: http://en.wikipedia.org/wiki/Sine_wave amplitude = screenXpixels * 0.25; frequency = 0.2; angFreq = 2 * pi * frequency; startPhase = 0; time = 0; % Sync us and get a time stamp vbl = Screen(‘Flip‘, window); waitframes = 1; % Maximum priority level topPriorityLevel = MaxPriority(window); Priority(topPriorityLevel); % Loop the animation until a key is pressed while ~KbCheck % Position of the square on this frame xpos = amplitude * sin(angFreq * time + startPhase); % Use the x position of the square to determine its color 根据x坐标来确定颜色变化率 colorMultiplier = abs(xpos) / amplitude; % Add this position to the screen center coordinate. This is the point % we want our square to oscillate around squareXpos = xCenter + xpos; % Center the rectangle on the centre of the screen centeredRect = CenterRectOnPointd(baseRect, squareXpos, yCenter); % Draw the rect to the screen Screen(‘FillRect‘, window, [1 - colorMultiplier 0 colorMultiplier],... centeredRect); % Flip to the screen vbl = Screen(‘Flip‘, window, vbl + (waitframes - 0.5) * ifi); % Increment the time time = time + ifi; end
6.Moving Size Change Square Demo: 使一个正方形在屏幕上呈正弦式横向运动，其大小取决于其屏幕上的位置
注：对矩形的中心点进行正弦式变化
% Make a base Rect of 200 by 200 pixels baseRect = [0 0 200 200]; % Set the color of the rect to red rectColor = [1 0 0]; % Our square will oscilate with a sine wave function to the left and right % of the screen. These are the parameters for the sine wave % See: http://en.wikipedia.org/wiki/Sine_wave amplitude = screenXpixels * 0.25; frequency = 0.2; angFreq = 2 * pi * frequency; startPhase = 0; time = 0; % Sync us and get a time stamp vbl = Screen(‘Flip‘, window); waitframes = 1; % Maximum priority level topPriorityLevel = MaxPriority(window); Priority(topPriorityLevel); % Loop the animation until a key is pressed while ~KbCheck % Position of the square on this frame 确定每一帧的位移量 xpos = amplitude * sin(angFreq * time + startPhase); % Use the x position of the square to determine its color 利用x坐标在确定矩形的颜色，但是实际上并没有用到 sizeMultiplier = abs(xpos) / amplitude; % Add this position to the screen center coordinate. This is the point 设置中心坐标 % we want our square to oscillate around squareXpos = xCenter + xpos; % Center the rectangle on the centre of the screen 将矩形调整到以屏幕中心点为中心的位置 centeredRect = CenterRectOnPointd(baseRect * sizeMultiplier,... squareXpos, yCenter); % Draw the rect to the screen Screen(‘FillRect‘, window, rectColor, centeredRect); % Flip to the screen vbl = Screen(‘Flip‘, window, vbl + (waitframes - 0.5) * ifi); % Increment the time time = time + ifi; end
PTBtutorials—Animating basic shapes and dots(1)
原文：https://www.cnblogs.com/zxpsyneuroscience/p/12619660.html