# PGraphics + noSmooth() + alpha = drawing artifacts
**URL:** https://discourse.processing.org/t/pgraphics-nosmooth-alpha-drawing-artifacts/7892
**Category:** Coding Questions
**Created:** [January 28, 2019, 12:44am UTC](https://discourse.processing.org/t/pgraphics-nosmooth-alpha-drawing-artifacts/7892 "2019-01-28T00:44:31Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Kevin](https://discourse.processing.org/u/Kevin)
#### Post date: [January 28, 2019, 12:44am UTC](https://discourse.processing.org/t/pgraphics-nosmooth-alpha-drawing-artifacts/7892/1 "2019-01-28T00:44:31Z")
**Note:** I also asked this question on Stack Overflow [here](https://stackoverflow.com/q/54408259/873165).
I have this sample code:
```auto
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 points in a couple rectangular areas:
If I remove the call to `pg.noSmooth()` or if I remove the alpha value in the `pg.stroke()` call, then it works fine:
If I replace the `pg.point()` call with `pg.ellipse()` or `pg.rect()` then it also works fine.
It seems like the combination of using a `PGraphics`, the `noSmooth()` function, the `point()` function, and an alpha value results in this buggy behavior. I’ve tried in Processing 3.3 and Processing 3.5.2 and I see the same behavior in both.
Am I missing something obvious?
---
### Author:  [@BennyHacker](https://discourse.processing.org/u/BennyHacker)
#### Post date: [January 28, 2019, 8:35pm UTC](https://discourse.processing.org/t/pgraphics-nosmooth-alpha-drawing-artifacts/7892/2 "2019-01-28T20:35:09Z")
After doing a bit of testing I’m starting to think it just might be a bug with processing’s aliasing/anti-aliasing. Maybe there’s a bug where it thinks the point is the ‘incorrect’ size and doesn’t need to be drawn?
I also noticed that using
**_pg.set(mouseX,mouseY,color(255))_**
works for whatever reason
---
### Author:  [@Kevin](https://discourse.processing.org/u/Kevin)
#### Post date: [January 28, 2019, 10:48pm UTC](https://discourse.processing.org/t/pgraphics-nosmooth-alpha-drawing-artifacts/7892/3 "2019-01-28T22:48:07Z")
Yeah, the `pg.set()` function works okay, even if it contains transparency:
```auto
color c = color(255, 255, 255, 64);
pg.set(mouseX, mouseY, c);
```
I’ve filed a bug on GitHub about this [here](https://github.com/processing/processing/issues/5777).
---
### Author:  [@Kevin](https://discourse.processing.org/u/Kevin)
#### Post date: [January 29, 2019, 6:06pm UTC](https://discourse.processing.org/t/pgraphics-nosmooth-alpha-drawing-artifacts/7892/4 "2019-01-29T18:06:53Z")
[This answer](https://stackoverflow.com/a/54420174/873165) from [George Profenza](https://stackoverflow.com/users/89766/george-profenza) provides more info.
Apparently the Java2D renderer draws a point as a line [here](https://github.com/processing/processing/blob/9c89b78e057f2898bb39b5768d06120369110841/core/src/processing/awt/PGraphicsJava2D.java#L1190):
```auto
static final float EPSILON = 0.0001f;
```
```auto
public void point(float x, float y) {
if (stroke) {
// if (strokeWeight > 1) {
line(x, y, x + EPSILON, y + EPSILON);
// } else {
// set((int) screenX(x, y), (int) screenY(x, y), strokeColor);
// }
}
```
We can reproduce this error by drawing our points as tiny lines:
```auto
PGraphics pg;
void setup() {
size(400, 500);
pg = createGraphics(width, height);
pg.noSmooth();
pg.beginDraw();
pg.background(0, 0, 255);
pg.stroke(255, 254);
for (int y = 0; y < pg.height; y+=2) {
for (int x = 0; x < pg.width; x+=2) {
//pg.point(x, y);
pointNoSmooth(pg, x, y);
}
}
pg.endDraw();
}
void pointNoSmooth(PGraphics pg, float x, float y) {
// any less than 0.75 distance between vertices
// and there's nothing to render with aliasing
float epsilon = 0.01;
pg.beginShape();
pg.vertex(x, y);
pg.vertex(x + epsilon, y);
pg.endShape();
}
void draw() {
image(pg, 0, 0, width, height);
}
```
With a small `epsilon` value, we see the same artifacts I was seeing:
If we increase `epsilon` to anything larger than `0.75`, then it renders correctly:
Interestingly, if we remove the alpha argument, then we don’t see any dots at all.
I’m going to update [the bug](https://github.com/processing/processing/issues/5777) with this info, but for my purposes I’m happy that I’m not doing something obviously wrong. Thanks again George!