# Shapes Shader

A simple shader that outputs 3 shapes : A quadrilateral( square/rect ), A Circle, A Polygon (Triangle to Infinitygon).

This shader can be used in fast level designing such as the shapes available on unity. The cover image is an example of a scene i designed with this shader, it took 5 minutes.

The parameters are :

Shape – (0, 1, 2) – 0 is Circle, 1 is Rect, 2 is Polygon

Poly Count – (3 – inf) – 3 is Triangle, 4 is Square, 5 is Pentagon and so on. (Only works if shape is a Polygon)

(Ignore the fog in the cover photo :/)

##### Shader code

```
shader_type canvas_item;
uniform int shape = 0;
uniform float poly_count = 3.0;
const float PI = 3.14159265359;
const float TWO_PI = 6.28318530718;
float Circle(vec2 st)
{
vec2 center = vec2(0.5) - st;
return step(length(center), 0.5);
}
float Square(vec2 st)
{
return 1.0;
}
float Triangle(vec2 st, float width)
{
st = st * 2.0 - 1.0;
if (poly_count > 2.0)
{
if (poly_count < 4.0)
{
st.y += 0.25;
}
}
float angle = atan(st.x, st.y) + radians(180.0);
float radius = TWO_PI / float(poly_count);
float dist = cos(floor(0.5 + angle / radius) * radius - angle) * length(st);
float poly = step(width, dist);
return 1.0 - poly;
}
void fragment()
{
vec2 st = UV;
st.y = 1.0 - st.y;
float sh;
if (shape == 0)
{
sh = Circle(st);
}
else if (shape == 1)
{
sh = Square(st);
}
else if (shape == 2)
{
sh = Triangle(st, 0.5);
}
vec3 color = vec3(sh);
color = 1.0 - color;
float alpha = 1.0 - color.r;
color = 1.0 - color;
COLOR = vec4(color, alpha);
}
```

Great utility shader! However, I think you accidentally hardcoded 3.0 on line 27 instead of using the ‘poly_count’ uniform. A suggestion, make poly_count an integer. That way you can easily use the up/down arrows in the Inspector.

i made poly_count a float so that it can be used in GLES2 as GLES2 doesn’t support the “float()” function. the harcoding will be fixed in a minute.

I have updated it 🙂

It works! There are some redundancies in the code, for example line 24, 36, and 62 can be reduced to one line each, but thanks for posting this and letting me learn how to draw shapes in GDSL.

(for example line 62-64 can just be reduced to “float alpha = color.r;”)

line 66 too