Too many arguments to constructor of TouchDesigner's - glsl

Question

I use TouchDesigner's GLSL. I want to try to make the color transparent like alpha but he will appear too many arguments to constructor of XXX
void main()
{
vec2 r = vUV.st;
vec3 backgroundColor = vec3(1.0,0,0,0);
vec3 axesColor = vec3(0.0, 0.0, 1.0);
vec3 gridColor = vec3(0.5);
// start by setting the background color. If pixel's value
// is not overwritten later, this color will be displayed.
vec3 pixel = backgroundColor;
// Draw the grid lines
// we used "const" because loop variables can only be manipulated
// by constant expressions.
const float tickWidth = 0.1;
for(float i=0.0; i<1.0; i+=tickWidth) {
// "i" is the line coordinate.
if(abs(r.x - i)<0.002) pixel = gridColor;
if(abs(r.y - i)<0.002) pixel = gridColor;
}
// Draw the axes
if( abs(r.x)<0.005 ) pixel = axesColor;
if( abs(r.y)<0.006 ) pixel = axesColor;
fragColor = TDOutputSwizzle(vec4(pixel, 1.0));
}

Answer 1

The issue is the line
vec3 backgroundColor = vec3(1.0,0,0,0);
You have passed 4 arguments to the constructor of vec3. A Vector constructor take the number of values that the vector stores.
Pass 3 singel floating point values to solve the issue:
vec3 backgroundColor = vec3(1.0, 0.0, 0.0);
The alpha channel is the 4th component. If you want to add an alpha channel, then you have to use vec4 instead of vec3:
void main()
{
vec2 r = vUV.st;
vec4 backgroundColor = vec4(1.0, 0.0, 0.0, 0.0); // red: 1, green: 0, blue: 0, alpha: 0
vec4 axesColor = vec3(0.0, 0.0, 1.0, 1.0); // red: 0, green: 0, blue: 1, alpha: 1
vec4 gridColor = vec3(0.5, 0.0, 0.0, 1.0); // red: 0.5, green: 0, blue: 0, alpha: 1
// start by setting the background color. If pixel's value
// is not overwritten later, this color will be displayed.
vec4 pixel = backgroundColor;
// Draw the grid lines
// we used "const" because loop variables can only be manipulated
// by constant expressions.
const float tickWidth = 0.1;
for(float i=0.0; i<1.0; i+=tickWidth) {
// "i" is the line coordinate.
if (abs(r.x - i) < 0.002 || abs(r.y - i) < 0.002)
pixel = gridColor;
}
// Draw the axes
if (abs(r.x) < 0.005 || abs(r.y) < 0.006)
pixel = axesColor;
fragColor = TDOutputSwizzle(pixel);
}