processing / processing/processing4

Text mis-aligned when scaling and using `textSize()` with `P2D`

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help wanted opengl
Dominant language
Java
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Description

Created by: Santarii

Expected Behavior

If I use the scale function and then use the textSize function to reverse that scaling, I expect to get the same result as just rendering the text without any scaling.

Current Behavior

In the default renderer the text is lower than it should be when scaled up then sized back down. In P2D the space between characters also changes.

Steps to Reproduce

float scale = 1;

void setup() {
  size(1920, 1080, P2D);
  textFont(createFont("Consolas", 256));
}

void draw() {
  scale += 1;
  scale(scale);
  background(0);
  textAlign(LEFT, TOP);
  textSize(256f/scale);
  text("Wow", 0, 0);
}

This code renders text, and each frame increases the scale, but the scale is exactly reversed with the textSize function. If the bug didn't exist, this would look like stationary unchanging text, however this is not the case.

Your Environment

  • Processing version: 4.0b6
  • Operating System and OS version: Windows 10 Home 64-bit. 10.0.19043 Build 19043.

Possible Causes / Solutions

It seems to not just be small values in textSize, even reasonable values mess with the alignment a bit, though very small values have a more significant effect.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the supplied Processing sketch with the P2D renderer, then compare it with the default renderer while scaling and applying the inverse textSize(). Investigate the renderer's text alignment and character-spacing behavior; done means the text remains visually stationary and consistently spaced as the scale changes.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
computer-graphics
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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