pgraphics

问题 In Processing's Java Mode, you use PGraphics objects by declaring them globally, setting them up with createGraphics() in setup() and then referring to them in draw(). In the Python mode, what to do is not so clear and doesn't seem to be explained by the documentation. You can't declare variables in Python and variables are not automatically global, i.e. if I just say in setup() c = createGraphics(400,400) and then in draw() say c.beginDraw() I get a NameError: global name 'c' is not defined

问题 Note: I also asked this question on the Processing forum here. I have this sample code: PGraphics pg; void setup() { size(400, 500); pg = createGraphics(width, height); pg.noSmooth(); pg.beginDraw(); pg.background(0, 0, 255); pg.endDraw(); } void draw() { if (mousePressed) { pg.beginDraw(); pg.stroke(255, 254); pg.point(mouseX, mouseY); pg.endDraw(); } image(pg, 0, 0, width, height); } I would expect this code to show a point wherever the user presses the mouse. Instead, I am only able to see

问题 Note: I also asked this question on the Processing forum here. I have this sample code: PGraphics pg; void setup() { size(400, 500); pg = createGraphics(width, height); pg.noSmooth(); pg.beginDraw(); pg.background(0, 0, 255); pg.endDraw(); } void draw() { if (mousePressed) { pg.beginDraw(); pg.stroke(255, 254); pg.point(mouseX, mouseY); pg.endDraw(); } image(pg, 0, 0, width, height); } I would expect this code to show a point wherever the user presses the mouse. Instead, I am only able to see

问题 Note: I also asked this question on the Processing forum here. I have this sample code: PGraphics pg; void setup() { size(400, 500); pg = createGraphics(width, height); pg.noSmooth(); pg.beginDraw(); pg.background(0, 0, 255); pg.endDraw(); } void draw() { if (mousePressed) { pg.beginDraw(); pg.stroke(255, 254); pg.point(mouseX, mouseY); pg.endDraw(); } image(pg, 0, 0, width, height); } I would expect this code to show a point wherever the user presses the mouse. Instead, I am only able to see

问题 Note: I also asked this question on the Processing forum here. I have this sample code: PGraphics pg; void setup() { size(400, 500); pg = createGraphics(width, height); pg.noSmooth(); pg.beginDraw(); pg.background(0, 0, 255); pg.endDraw(); } void draw() { if (mousePressed) { pg.beginDraw(); pg.stroke(255, 254); pg.point(mouseX, mouseY); pg.endDraw(); } image(pg, 0, 0, width, height); } I would expect this code to show a point wherever the user presses the mouse. Instead, I am only able to see

问题 This is a follow-up of my question: Make the cursor a self-drawn image. I have a paint a picture application. The latest working version can be found here: https://knowledgeablekangaroo.github.io/paint-a-picture-backup/, where the code can be found in F12 > Sources > paint-a-picture.js . The user can choose a color, set the background, set the thickness, shape, and opacity. There is also an eraser functionality. I want there to be a better user experience, so I am trying to draw the eraser