Interactivity & Widgets

Since Slope works on top of polyscope, you keep the control over the camera with usual mouse control.

To make interactive presentations, you can use ImGui widgets as a primitive:

    float* f = new float(1); // make sure to allocate on heap

    show << Point::Add([f](TimeObject t) {
        scalar th = (*f)*t.inner_time;
        return vec(cos(th),sin(th),0);
    });

    show << ImGuiWidgets::Add([f]() {
        ImGui::SliderFloat("speed",f,0,10);
    },"window name");

ImGuiWidgets::Add(std::function<void()>& callback,std::string window_name)

Tunable parameters

For scalar-like parameters that need tuning for animation, you can add a Params object. runtime-tunable, persistent parameters next to the code that uses them:

auto amp   = Params::Add("amplitude", 0.2, 0., 1.);  // slider in [0,1]
auto speed = Params::Add("speed", 1.);               // unconstrained drag

spot->setUpdater([=](TimeObject t) {
    deform(spot, (scalar)amp, (scalar)speed * t.inner_time);
});

Params::Add(name, default, min, max), also AddInt, AddBool, AddColor, AddVec2, AddVec, AddDir

The handle reads the live value (a plain conversion, usable in hot loops). Pressing A opens the Tuner panel, showing the parameters read by the current slide's updaters (a checkbox reveals all of them), grouped by their "group/name" prefix. The polyscope camera is not affected while you tweak.

Edited values are saved with Ctrl+S to views/params.json. Only ever-edited parameters are written, so untouched ones keep following their code defaults. The file is loaded back on startup, and hot-reloaded when edited by hand.

Handles

A position is easier to aim than to type, so the geometric parameters carry a widget on top of their sliders:

Type	Button	Widget
vec3	3D	a translation gizmo in the scene, the same one the T editor uses for transforms
dir (AddDir)		a ball oriented like the camera: the mouse aims the unit vector, right click flips the hemisphere
vec2	2D	a crosshair dragged on the screen

all and none, next to the panel's checkbox, switch every handle of the listed parameters on or off at once. While a handle is live the slide stops taking mouse input, so dragging never spins the camera by accident, and closing the panel puts everything back.

A vec2 parameter is in screen coordinates: 0..1 across the window, y up. That is gl_FragCoord's convention, the opposite of the screen anchors', and it is what lets a shader put an object exactly under its handle:

#include <camera.glsl>
uniform vec2 center;

void main() {
    float d = length((screenPoint() - center) * iWindowSize);   // window pixels
    ...
}

screenPoint() reports where this fragment falls on the window, so the agreement holds wherever the shader is placed and whatever its resolution: is. It is the 2D counterpart of polyscopeRay for 3D scenes.