Fix: allow single-arg atan() outside strands; add unit test

[Abhayaj247]

Resolves #8092

• The single-argument atan(x) was incorrectly treated as GLSL-only in strands, causing a friendly error and returning undefined when called outside a shader. This mirrors the noise() override issue fixed in Fix noise() getting overridden; add tests #8036.
• The fix marks the 1-arg overload as a normal p5 function while keeping the 2-arg GLSL overload atan(y, x) strands-only.

Changes :

• src/webgl/ShaderGenerator.js

  • In builtInGLSLFunctions, set:
    • atan single-arg overload: isp5Function: true
    • atan two-arg overload: remains isp5Function: false

• test/unit/visual/cases/math.js

  • Add atan_outside_strands visual integration test that draws the value of atan(0.5) to ensure it evaluates and no friendly error is triggered.

• test/unit/spec.js

  • Include the new visual test suite entry visual/cases/math.

Screenshots of the change :

• Visual test creates baseline showing text like “atan(0.5) ≈ 0.464”; subsequent runs match the baseline.

PR Checklist :

• npm run lint passes
• Inline reference is included / updated (function behavior unchanged; no reference edits needed)
• Unit tests are included / updated (added visual/integration test)

[davepagurek]

Thanks for making this! Since the atan test is just checking the value of the result, I think it makes more sense to do a regular unit test rather than a visual test (it's a lot computationally cheaper to compare numbers with expect(val).toEqual(...) than to compare all the pixels in an image, do you think we could put the test in one of our unit test files instead?

[Abhayaj247]

Thanks for the feedback @davepagurek , I’ve moved the atan tests to a dedicated unit test file at test/unit/math/atan.js . The tests now verify correct numerical results for single-argument usage and ensure the two-argument (GLSL-only) case returns undefined outside of strands. This keeps the tests efficient, focused, and aligned with the intended testing strategy - helping maintain clarity in the suite.

Please let me know if you need any further adjustments.

[davepagurek]

Can we test the actual atan without testing a mock version? I think the only thing we really need a test for is just that, outside of strands, you can call atan with one argument, which it already supports without needing an override.

[davepagurek]

The reason being, it becomes a bit unclear how much of the functionality we're testing is just in the mock once we start doing this.

[Abhayaj247]

Hi @davepagurek ,

I’ve updated the atan unit test to only verify single-argument behavior (in both radians and degrees) using the actual function, without overriding or mocking it.

import trigonometry from '../../../src/math/trigonometry.js';
import { assert } from 'chai';

suite('atan', function() {
  const mockP5 = {
    RADIANS: 'radians',
    DEGREES: 'degrees',
    _validateParameters: () => {}
  };
  const mockP5Prototype = {};

  beforeEach(function() {
    mockP5Prototype._angleMode = mockP5.RADIANS;
    mockP5Prototype.angleMode = function(mode) {
      this._angleMode = mode;
    };
    trigonometry(mockP5, mockP5Prototype);
  });

  test('should return the correct value for atan(0.5) in radians', function() {
    mockP5Prototype.angleMode(mockP5.RADIANS);
    const expected = Math.atan(0.5);
    const actual = mockP5Prototype.atan(0.5);
    assert.closeTo(actual, expected, 1e-10);
  });

  test('should return the correct value for atan(0.5) in degrees', function() {
    mockP5Prototype.angleMode(mockP5.DEGREES);
    const expected = Math.atan(0.5) * 180 / Math.PI;
    const actual = mockP5Prototype.atan(0.5);
    assert.closeTo(actual, expected, 1e-10);
  });
});

Could you please confirm if this approach looks good before I commit and push the changes?

Thanks!

[davepagurek]

That approach looks right! maybe just evaluate the two functions on a calculator to get as specific of a value to compare to as possible for your radians and degrees cases.

[Abhayaj247]

Thanks for the clarification @davepagurek. I’ve updated the tests to directly compare against pre-calculated values for atan(0.5) in both radians and degrees. Here’s the full updated test file :

import trigonometry from '../../../src/math/trigonometry.js';
import { assert } from 'chai';

suite('atan', function() {
  const mockP5 = {
    RADIANS: 'radians',
    DEGREES: 'degrees',
    _validateParameters: () => {}
  };
  const mockP5Prototype = {};

  beforeEach(function() {
    mockP5Prototype._angleMode = mockP5.RADIANS;
    mockP5Prototype.angleMode = function(mode) {
      this._angleMode = mode;
    };
    trigonometry(mockP5, mockP5Prototype);
  });

  test('should return the correct value for atan(0.5) in radians', function() {
    mockP5Prototype.angleMode(mockP5.RADIANS);
    const expected = 0.4636476090008061; // pre-calculated value
    const actual = mockP5Prototype.atan(0.5);
    assert.closeTo(actual, expected, 1e-10);
  });

  test('should return the correct value for atan(0.5) in degrees', function() {
    mockP5Prototype.angleMode(mockP5.DEGREES);
    const expected = 26.56505117707799; // pre-calculated value
    const actual = mockP5Prototype.atan(0.5);
    assert.closeTo(actual, expected, 1e-10);
  });
});

Could you confirm if this looks good before I push the changes? Happy to make any further adjustments if needed.

[davepagurek]

looks good!

[Abhayaj247]

Thank you for reviewing and confirming, @davepagurek! I’ve pushed the changes accordingly. Please let me know if there’s anything else needed.

[davepagurek]

thanks for the PR!

[Abhayaj247]

Thank you for your guidance throughout this process. I look forward to contributing more.