Shader is like The Function of Microsoft Excel. You write a function, it will handle the form-data for you.

If we treat the data in the form as input pixels, the calculated form as output pixels, Codes in PixelsWorld is the function in Microsoft Excel

## E.g. Make picture brighter

To make a picture brighter, the simplest approach is just to add the R, G, B by a number. If in Excel, we need to do something like this:

Then we have made all pixels data "brighter"!

Here is what we need to write in PixelsWorld:

outColor=getColor(uv)+vec4(0.2);


It means: Get the input pixels (getColor) in current location (uv), and add the 4D vector RGBA by (0.2,0.2,0.2,0.2) (+vec4(0.2)). Finally, send (=) the result to the output pixel(outColor).

But if we only write this single line, PixelsWorld cannot work fine. We need to add this line inside a "shell" to make it work. The complete version is this:

void main(){
outColor=getColor(uv)+vec4(0.2);
}


### Result

Mostly we don't just add 0.2 to the picture. We want it to be more controllable. So we can replace the 0.2 with slider[0]. In this way, we can change the value in the Parameters panel to change the brightness of your picture.

void main(){
outColor=getColor(uv)+vec4(slider[0]);
}


But you can find that, if the value is negative, the picture will be transparent, we don't want this to happen. Namely, we need to avoid modifying the Alpha channel of the picture.

void main(){
vec4 inColor = getColor(uv);
inColor.rgb = inColor.rgb + vec3(slider[0]);
outColor = inColor;
}


It means: Save the input pixel into a temporary variable inColor, Add the value of slider[0] to the RGB of inColor, then send the inColor to the outColor.

### Save to preset

Finally, we can save the code as a preset for the next use. Go to the Preset management to learn more details.

## Congratulations!

You have already mastered most of PixelsWorld!

In addition to writing codes by yourself, you can go to the shadertoy, find some interesting code, and run it in PixelsWorld. See this to learn how to use code from shadertoy.