mesh on round objects

General
1

I had to use triangulate(points) in order to see the mesh rendering in color - its a circle I pre-calculated myself. How can avoid using this function? Reason: When triangulating, I cannot outline my mesh with line() anymore, because each tri gets its own outline and it looks zig-zaged and outlined … just a mess…

2

There are probably smarter ways, but the 2 that come to mind are

  1. Pre-render a ellipse with a stroke and set the mesh texture to it
  2. Make a slightly bigger mesh behind it that’s the stroke colour
3

I made it differently. Pre-calculated ellipse with modified version of Simeon’s code for star-mesh. Drawn the mesh with those vertices. On top, drawn an (out-)line, by using mesh’s every third coordinate - that are the exact coordinates for outline.

Two same meshes is nonsense. double data to load every frame… Thanks anyway.

4

You can ‘save’ them as an image using image() so you render two meshes as one image

5

I was just throwing some ideas around, no need to be rude about it.

6

@Luatee yes, I thought about that, but this would take away the possibility to change colors, etc, at runntime. thank you for that idea)
@colincapurso, I’m really sorry about that. excuse me please! And thank you all for the fresh ideas!

7

I think Ive solved it, It works, currently. If somebody has an idea how to compute automatic sides cound on circle - comments are welcome! currently I do: (radiusX + radiusY) / 2
but this is too havy yet.

8

Hello @se24vad. Is your circular mesh made up of triangles, each with one vertex at the centre and the other two on the circumference? You could set the uv coordinates and use a simple fragment shader so as to render a line between the vertices on the circumference.


function setup()
    myMesh = mesh()
    local ver = {}
    local uv = {}
    local n = 60
    local da = 2 * math.pi / n
    local r = math.min(WIDTH / 2, HEIGHT / 2)
    for i = 0, n - 1 do
        local a = da * i
        ver[i * 3 + 1] = vec2(r * math.cos(a), r * math.sin(a))
        ver[i * 3 + 2] = vec2(r * math.cos(a + da),
            r * math.sin(a + da))
        ver[i * 3 + 3] = vec2(0, 0)
        uv[i * 3 + 1] = vec2(0, 0)
        uv[i * 3 + 2] = vec2(1, 0)
        uv[i * 3 + 3] = vec2(0.5, 1)
    end
    myMesh.vertices = ver
    myMesh.texCoords = uv
    myMesh.shader = shader(outerEdge.fragmentShader,
        outerEdge.vertexShader)
end

function draw()
    background(0)
    translate(WIDTH / 2, HEIGHT / 2)
    myMesh:draw()
end

outerEdge = {
fragmentShader = [[
uniform mat4 modelViewProjection;

attribute vec4 position;
attribute vec2 texCoord;

varying highp vec2 vTexCoord;

void main() {
    vTexCoord = texCoord;
    gl_Position = modelViewProjection * position;
}
]],
vertexShader = [[
precision highp float;

varying vec2 vTexCoord;

void main() {
    vec4 col = vec4(1.0);
    if (vTexCoord.y > 0.05)
        col = vec4(vec3(0.5, 0.5, 0.0), 1.0);
    gl_FragColor = col;
}
]]}