MetaCoreEngineV2/samples/orbit_alt_drag.py

import math

from direct.showbase.ShowBase import ShowBase
from panda3d.core import KeyboardButton, MouseButton, Point2, Vec3, loadPrcFileData


# Basic window settings for clarity.
loadPrcFileData("", "window-title Alt+LMB Orbit Demo")
loadPrcFileData("", "show-frame-rate-meter #t")


class OrbitDemo(ShowBase):
    def __init__(self):
        super().__init__()
        self.disableMouse()  # We manage the camera manually.

        self.focus_distance = 8.0
        self.orbit_active = False
        self.pan_active = False
        self.radius = self.focus_distance
        self.azimuth = 0.0
        self.elevation = 0.0
        self.last_mouse = None
        self.last_mouse_pan = None
        self.pivot = Vec3(0, 0, 0)

        self._setup_scene()
        self._refresh_camera_from_angles()

        self.accept("mouse1", self._on_mouse1_down)
        self.accept("alt-mouse1", self._on_mouse1_down)
        self.accept("mouse1-up", self._on_mouse1_up)
        self.accept("mouse2", self._on_mouse2_down)
        self.accept("mouse2-up", self._on_mouse2_up)
        self.accept("wheel_up", lambda: self._on_wheel(1))
        self.accept("wheel_down", lambda: self._on_wheel(-1))
        
        bt = self.buttonThrowers[0].node()
        bt.setButtonDownEvent("btn-down")
        bt.setButtonUpEvent("btn-up")
        bt.setKeystrokeEvent("keystroke")
        self.accept("btn-down", lambda name: print("btn-down:", name))
        self.accept("btn-up", lambda name: print("btn-up:", name))
        self.accept("keystroke", lambda key: print("key:", key))
        self.taskMgr.add(self._update_orbit, "update_orbit")

    def _setup_scene(self):
        env = self.loader.loadModel("models/environment")
        env.reparentTo(self.render)
        env.setScale(0.1)
        env.setPos(-8, 42, 0)

        # Small marker that shows the current orbit center.
        self.focus_marker = self.loader.loadModel("models/smiley")
        self.focus_marker.reparentTo(self.render)
        self.focus_marker.setScale(0.15)
        self.focus_marker.setColor(1, 0.9, 0.2, 1)
        self.focus_marker.hide()  # Shown only while orbiting.

    def _point_in_front(self):
        forward = self.camera.getQuat(self.render).getForward()
        return self.camera.getPos(self.render) + forward.normalized() * self.focus_distance

    def _sync_angles_from_camera(self):
        offset = self.camera.getPos(self.render) - self.pivot
        self.radius = offset.length()
        if self.radius < 1e-5:
            self.radius = self.focus_distance
            offset = Vec3(0, -self.radius, 0)
        self.azimuth = math.atan2(offset.x, offset.y)
        self.elevation = math.asin(max(-1.0, min(1.0, offset.z / self.radius)))

    def _refresh_camera_from_angles(self):
        # print("Orbiting around:", self.pivot)
        cos_el = math.cos(self.elevation)
        x = math.sin(self.azimuth) * cos_el
        y = math.cos(self.azimuth) * cos_el
        z = math.sin(self.elevation)

        self.camera.setPos(self.pivot + Vec3(x, y, z) * self.radius)
        self.camera.lookAt(self.pivot)

    def _on_mouse1_down(self):
        self.orbit_active = True
        print(self.orbit_active)
        self.pivot = self._point_in_front()
        self.focus_marker.setPos(self.pivot)
        self.focus_marker.show()
        self._sync_angles_from_camera()
        self.last_mouse = Point2(self.mouseWatcherNode.getMouse())

    def _on_mouse1_up(self):
        self.orbit_active = False
        self.last_mouse = None
        self.focus_marker.hide()
        print(self.orbit_active)

    def _on_mouse2_down(self):
        if not self.mouseWatcherNode.hasMouse():
            return
        self.pan_active = True
        self.last_mouse_pan = Point2(self.mouseWatcherNode.getMouse())

    def _on_mouse2_up(self):
        self.pan_active = False
        self.last_mouse_pan = None

    def _on_wheel(self, direction):
        # direction: +1 for wheel_up (zoom in), -1 for wheel_down (zoom out)
        zoom_factor = 0.9 if direction > 0 else 1.1
        self.radius = max(0.5, min(200.0, self.radius * zoom_factor))
        self._refresh_camera_from_angles()

    def _update_orbit(self, task):
        # Middle mouse pan (translates camera and pivot together).
        if self.pan_active and self.mouseWatcherNode.hasMouse():
            current = Point2(self.mouseWatcherNode.getMouse())
            if self.last_mouse_pan is not None:
                delta = current - self.last_mouse_pan
                right = self.camera.getQuat(self.render).getRight()
                up = self.camera.getQuat(self.render).getUp()
                pan_scale = self.radius * 0.8
                offset = (right * delta.x + up * delta.y) * pan_scale
                self.camera.setPos(self.camera.getPos(self.render) + offset)
                self.pivot += offset
                self._sync_angles_from_camera()
            self.last_mouse_pan = current
        elif self.pan_active and not self.mouseWatcherNode.isButtonDown(MouseButton.two()):
            self._on_mouse2_up()

        if not self.orbit_active:
            return task.cont

        if not self.mouseWatcherNode.isButtonDown(MouseButton.one()) or not self.mouseWatcherNode.isButtonDown(KeyboardButton.alt()):
            # print("Press Alt+LMB to activate orbit mode.")
            return task.cont

        if not self.mouseWatcherNode.hasMouse() or self.last_mouse is None:
            print("Mouse not available.")
            return task.cont

        current = Point2(self.mouseWatcherNode.getMouse())
        delta = current - self.last_mouse
        self.last_mouse = current

        # Screen space is [-1, 1], so multiply by a comfortable radians-per-unit factor.
        rot_speed = math.pi  # 180° per full screen swipe.
        self.azimuth += delta.x * rot_speed
        self.elevation -= delta.y * rot_speed
        self.elevation = max(math.radians(-85.0), min(math.radians(85.0), self.elevation))

        self._refresh_camera_from_angles()
        return task.cont


if __name__ == "__main__":
    app = OrbitDemo()
    app.run()