feat: Render 3D cube with camera controls (zoom, pan, rotate)

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

CMakeLists.txt

@@ -8,11 +8,12 @@ set(CMAKE_AUTOMOC ON)
 set(CMAKE_AUTORCC ON)
 set(CMAKE_AUTOUIC ON)
 
-find_package(Qt6 COMPONENTS Widgets REQUIRED)
+find_package(Qt6 COMPONENTS Widgets OpenGLWidgets REQUIRED)
 
 add_executable(OpenCAD
     src/main.cpp
     src/MainWindow.cpp
+    src/ViewportWidget.cpp
 )
 
-target_link_libraries(OpenCAD PRIVATE Qt6::Widgets)
+target_link_libraries(OpenCAD PRIVATE Qt6::Widgets Qt6::OpenGLWidgets)

src/MainWindow.cpp

@@ -1,7 +1,7 @@
 #include "MainWindow.h"
+#include "ViewportWidget.h"
 
 #include <QToolBar>
-#include <QWidget>
 
 MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent)
@@ -11,7 +11,6 @@ MainWindow::MainWindow(QWidget *parent)
 
     QToolBar *toolBar = addToolBar("Tools");
 
-    QWidget *viewport = new QWidget;
+    ViewportWidget *viewport = new ViewportWidget;
-    viewport->setStyleSheet("background-color: darkgray;");
     setCentralWidget(viewport);
 }

src/ViewportWidget.cpp

@@ -0,0 +1,123 @@
+#include "ViewportWidget.h"
+#include <QMouseEvent>
+#include <QWheelEvent>
+#include <QApplication>
+
+ViewportWidget::ViewportWidget(QWidget *parent)
+    : QOpenGLWidget(parent)
+{
+}
+
+void ViewportWidget::initializeGL()
+{
+    initializeOpenGLFunctions();
+    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+    glEnable(GL_DEPTH_TEST);
+}
+
+void ViewportWidget::paintGL()
+{
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    QMatrix4x4 model;
+    model.translate(panX, panY, zoom);
+    model.rotate(xRot / 16.0f, 1, 0, 0);
+    model.rotate(yRot / 16.0f, 0, 1, 0);
+
+    // For simplicity, we'll use a fixed-function pipeline style for drawing.
+    // In a real app, this would use shaders.
+    glMatrixMode(GL_PROJECTION);
+    glLoadMatrixf(projection.constData());
+
+    glMatrixMode(GL_MODELVIEW);
+    glLoadMatrixf(model.constData());
+
+    drawCube();
+}
+
+void ViewportWidget::resizeGL(int w, int h)
+{
+    projection.setToIdentity();
+    projection.perspective(45.0f, w / float(h), 0.01f, 100.0f);
+}
+
+void ViewportWidget::mousePressEvent(QMouseEvent *event)
+{
+    lastPos = event->pos();
+}
+
+void ViewportWidget::mouseMoveEvent(QMouseEvent *event)
+{
+    int dx = event->pos().x() - lastPos.x();
+    int dy = event->pos().y() - lastPos.y();
+
+    if (event->buttons() & Qt::MiddleButton) {
+        if (QApplication::keyboardModifiers() & Qt::ShiftModifier) {
+            // Pan
+            panX += dx / 100.0f;
+            panY -= dy / 100.0f;
+        } else {
+            // Rotate
+            xRot += 8 * dy;
+            yRot += 8 * dx;
+        }
+    }
+    lastPos = event->pos();
+    update();
+}
+
+void ViewportWidget::wheelEvent(QWheelEvent *event)
+{
+    QPoint numDegrees = event->angleDelta() / 8;
+    if (!numDegrees.isNull()) {
+        zoom += numDegrees.y() / 5.0f;
+    }
+    update();
+}
+
+void ViewportWidget::drawCube()
+{
+    glBegin(GL_QUADS);
+    // Front face
+    glColor3f(1.0, 0.0, 0.0);
+    glVertex3f(-0.5, -0.5, 0.5);
+    glVertex3f(0.5, -0.5, 0.5);
+    glVertex3f(0.5, 0.5, 0.5);
+    glVertex3f(-0.5, 0.5, 0.5);
+
+    // Back face
+    glColor3f(0.0, 1.0, 0.0);
+    glVertex3f(-0.5, -0.5, -0.5);
+    glVertex3f(-0.5, 0.5, -0.5);
+    glVertex3f(0.5, 0.5, -0.5);
+    glVertex3f(0.5, -0.5, -0.5);
+
+    // Top face
+    glColor3f(0.0, 0.0, 1.0);
+    glVertex3f(-0.5, 0.5, -0.5);
+    glVertex3f(-0.5, 0.5, 0.5);
+    glVertex3f(0.5, 0.5, 0.5);
+    glVertex3f(0.5, 0.5, -0.5);
+
+    // Bottom face
+    glColor3f(1.0, 1.0, 0.0);
+    glVertex3f(-0.5, -0.5, -0.5);
+    glVertex3f(0.5, -0.5, -0.5);
+    glVertex3f(0.5, -0.5, 0.5);
+    glVertex3f(-0.5, -0.5, 0.5);
+
+    // Right face
+    glColor3f(1.0, 0.0, 1.0);
+    glVertex3f(0.5, -0.5, -0.5);
+    glVertex3f(0.5, 0.5, -0.5);
+    glVertex3f(0.5, 0.5, 0.5);
+    glVertex3f(0.5, -0.5, 0.5);
+
+    // Left face
+    glColor3f(0.0, 1.0, 1.0);
+    glVertex3f(-0.5, -0.5, -0.5);
+    glVertex3f(-0.5, -0.5, 0.5);
+    glVertex3f(-0.5, 0.5, 0.5);
+    glVertex3f(-0.5, 0.5, -0.5);
+    glEnd();
+}

src/ViewportWidget.h

@@ -0,0 +1,38 @@
+#ifndef VIEWPORTWIDGET_H
+#define VIEWPORTWIDGET_H
+
+#include <QOpenGLWidget>
+#include <QOpenGLFunctions>
+#include <QMatrix4x4>
+#include <QPoint>
+
+class ViewportWidget : public QOpenGLWidget, protected QOpenGLFunctions
+{
+    Q_OBJECT
+
+public:
+    explicit ViewportWidget(QWidget *parent = nullptr);
+
+protected:
+    void initializeGL() override;
+    void paintGL() override;
+    void resizeGL(int w, int h) override;
+
+    void mousePressEvent(QMouseEvent *event) override;
+    void mouseMoveEvent(QMouseEvent *event) override;
+    void wheelEvent(QWheelEvent *event) override;
+
+private:
+    void drawCube();
+
+    QMatrix4x4 projection;
+
+    float xRot = 0;
+    float yRot = 0;
+    float zoom = -5.0f;
+    float panX = 0;
+    float panY = 0;
+    QPoint lastPos;
+};
+
+#endif // VIEWPORTWIDGET_H