Using a shader - solved

Shaders
1

I have made a timer shader based on the arc shader which should show a countdown like timer and it works fine in the shader lab, but when I try to use it in a project it doesn’t work. there are no error messages, just a blank screen. Am I doing something wrong?

2 
-- Main
displayMode(STANDARD)

function setup()
    
    timeshader={
    vertexShader=[[
    //
// Vertex shader: Timer
//

uniform mat4 modelViewProjection;

attribute vec4 position;
attribute vec2 texCoord;

varying highp vec2 vTexCoord;

void main() {
    vTexCoord = texCoord;
    gl_Position = modelViewProjection * position;
}

    ]],
    fragmentShader=[[
    //
// Fragment shader: Timer
//

precision highp float;

uniform float size;
uniform float a1;
uniform float a2;
uniform vec4 color;

varying vec2 vTexCoord;

void main() {
    vec4 col = vec4(0.0);
    vec2 r = vTexCoord - vec2(0.5);
    float d = length(r);
    if (d > size && d < 0.5) {
// this pixel is within the outer and outside the inner ring(s)
        float a = atan(r.y, r.x);
        if (a2 > a1) {
            if (a > a1 && a < a2) {
                col = color;
            }
        } else {
            if (a > a1 || a < a2) {
                col = color;
            }
        }
    }
    gl_FragColor = col;
}
    ]]
    }

    m = mesh()
    
    m.shader = shader(timeshader.vertexShader,timeshader.fragmentShader)
    
    r=m:addRect(0, 0, 0, 0)
    -- m:setRectColor(i, 255,0,0)
end

-- This function gets called once every frame
function draw()
    -- This sets a dark background color
    background(0, 0, 0, 255)

    -- This sets the line thickness
    strokeWidth(5)
    m:setRect(r,WIDTH/2,HEIGHT/2,100,100)
    m.shader.a1=math.fmod(ElapsedTime,math.pi*2)-math.pi
    m.shader.a2=-math.pi
    m.shader.color=vec4(0,1,0,1)
    m.shader.size=0.2
    
    -- Draw the mesh
    m:draw()
end

```
3

rIdx needs to have a size! The last two parameters of addRect need to be much greater then 0 (width and height)

4

@Luatee i fixed that but it stil won’t work

5

The shader doesn’t work in the shader lab for me.

Another problem might be the color uniform’s value, though. You want to set it to color(255,255,0,255), not vec4(1,1,0,1).

6

Sorry this was my fault. I didn’t supply the correct uniforms.
The code should work now