Segments

Segments

Segments(
    positions: Transform | Buffer,
    line_caps: Transform | Buffer | LineCap,
    line_colors: Transform | Buffer | Color,
    line_widths: Transform | Buffer | float,
)

Segments are line segments between two vertices. They can be colored and styled (dash pattern). They possess a thickness but always face the viewer such that their apparent thickness is constant. Their end points (caps) can be styled following the SVG specification (butt, round or cap).

IN/OUT variables

// Rendering stage 1
in uniform vec4 viewport;                     // in("viewport")
in attribute [ vec2 | vec3 ] positions;       // in("positions")
in [ attribute | uniform ] int line_caps;     // in("fill_colors")
in [ attribute | uniform ] vec4 line_colors;  // in("line_colors")
in [ attribute | uniform ] float line_widths; // in("line_widths")

// Rendering stage 2
out attribute vec3 screen;                    // out("screen[positions]")
out attribute vec3 segments;                  // out("screen[segments]")

// Rendering stage 3
out attribute int line_caps;                  // out("line_caps")
out attribute vec4 line_colors;               // out("line_colors")
out attribute float line_widths;              // out("line_widths")

Example

PYTHONTEXTJSON

positions = core.Buffer(2*3, np.dtype(np.float32))
markers = visual.Segments(positions,
                          line_caps=core.LineCap.round,
                          line_colors=(0,0,0,0),
                          line_widths=0.0)

1. COMMAND
     - METHOD: "core.Buffer" (str)
     - COMMAND_ID: 1 (int)
     - TIMESTAMP: 2025-03-18T15:02:34.095178 (datetime)
   PARAMETERS
     - OBJECT_ID: 1 (int)
     - COUNT: 6 (int)
     - DTYPE: float32 (dtype)
     - DATA: None (memoryview | bytes)

2. COMMAND
     - METHOD: "visual.Segments" (str)
     - COMMAND_ID: 2 (int)
     - TIMESTAMP: 2025-03-18T15:02:34.095279 (datetime)
   PARAMETERS
     - OBJECT_ID: 2 (int)
     - POSITIONS_ID: 1 (Transform | Buffer)
     - LINE_CAPS: 2 (Transform | Buffer | LineCap)
     - LINE_COLORS: Color(r=0, g=0, b=0, a=0) (converted) (Transform | Buffer | Color)
     - LINE_WIDTHS: 0.0 (Transform | Buffer | float)

{
  "jsonrpc": "2.0",
  "commands": [
    {
      "method": "core.Buffer",
      "id": 1,
      "timestamp": 1742306554.095178,
      "parameters": {
        "id": 1,
        "count": 6,
        "dtype": "float32",
        "data": null
      }
    },
    {
      "method": "visual.Segments",
      "id": 2,
      "timestamp": 1742306554.095279,
      "parameters": {
        "id": 2,
        "positions(id)": 1,
        "line_caps": 2,
        "line_colors": [
          0,
          0,
          0,
          0
        ],
        "line_widths": 0.0
      }
    }
  ]
}

Create a visual of n segments at given positions with given line_colors, line_widths and line_caps.

Parameters:

Name	Type	Description	Default
positions	Transform | Buffer	Segments positions (2,vec3)	required
line_caps	Transform | Buffer | LineCap	Segments end caps (int)	required
line_colors	Transform | Buffer | Color	Segments line colors (vec4)	required
line_widths	Transform | Buffer | Measure	Segments line width (float)	required

render

render(
    viewport: Viewport,
    model: Matrix = None,
    view: Matrix = None,
    proj: Matrix = None,
)

Render the visual on viewport using the given model, view, proj matrices

Parameters:

Name	Type	Description	Default
viewport	Viewport	Viewport where to render the visual	required
model	Matrix	Model matrix to use for rendering	None
view	Matrix	View matrix to use for rendering	None
proj	Matrix	Projection matrix to use for rendering	None