feat: Add sketch creation with plane selection, oriented grid and labeled axes

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

src/ViewportWidget.cpp

@@ -1,18 +1,24 @@
 #include "ViewportWidget.h"
 #include "ViewCube.h"
+#include "SketchGrid.h"
 #include <QMouseEvent>
 #include <QWheelEvent>
 #include <QApplication>
+#include <QPainter>
+#include <QWheelEvent>
+#include <QApplication>
 
 ViewportWidget::ViewportWidget(QWidget *parent)
     : QOpenGLWidget(parent)
 {
     m_viewCube = new ViewCube();
+    m_sketchGrid = new SketchGrid();
 }
 
 ViewportWidget::~ViewportWidget()
 {
     delete m_viewCube;
+    delete m_sketchGrid;
 }
 
 void ViewportWidget::initializeGL()
@@ -21,6 +27,7 @@ void ViewportWidget::initializeGL()
     glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
     glEnable(GL_DEPTH_TEST);
     m_viewCube->initializeGL();
+    m_sketchGrid->initializeGL();
 }
 
 void ViewportWidget::paintGL()
@@ -42,6 +49,10 @@ void ViewportWidget::paintGL()
     glMatrixMode(GL_MODELVIEW);
     glLoadMatrixf(model.constData());
 
+    if (m_currentPlane != SketchPlane::NONE) {
+        m_sketchGrid->paintGL(static_cast<SketchGrid::SketchPlane>(m_currentPlane), projection, model);
+    }
+
     // View cube rendering
     QMatrix4x4 viewCubeModel;
     viewCubeModel.rotate(xRot / 16.0f, 1, 0, 0);
@@ -49,6 +60,12 @@ void ViewportWidget::paintGL()
     m_viewCube->paintGL(viewCubeModel, width(), height());
 
     glViewport(0, 0, width(), height());
+
+    if (m_currentPlane != SketchPlane::NONE) {
+        QPainter painter(this);
+        drawAxisLabels(painter, model, projection);
+        painter.end();
+    }
 }
 
 void ViewportWidget::resizeGL(int w, int h)
@@ -90,3 +107,77 @@ void ViewportWidget::wheelEvent(QWheelEvent *event)
     }
     update();
 }
+
+void ViewportWidget::startSketch(SketchPlane plane)
+{
+    m_currentPlane = plane;
+    panX = 0;
+    panY = 0;
+    zoom = -20.0f; // Zoom out to see the grid
+
+    switch (plane) {
+        case SketchPlane::XY: // Top view
+            xRot = -90 * 16;
+            yRot = 0;
+            break;
+        case SketchPlane::XZ: // Front view
+            xRot = 0;
+            yRot = 0;
+            break;
+        case SketchPlane::YZ: // Right view
+            xRot = 0;
+            yRot = 90 * 16;
+            break;
+        case SketchPlane::NONE:
+            break;
+    }
+    update();
+}
+
+QVector3D ViewportWidget::project(const QVector3D& worldCoord, const QMatrix4x4& modelView, const QMatrix4x4& projection, const QRect& viewport)
+{
+    QVector4D clipCoord = projection * modelView * QVector4D(worldCoord, 1.0);
+    if (qFuzzyCompare(clipCoord.w(), 0.0f)) {
+        return QVector3D(-1, -1, -1);
+    }
+
+    QVector3D ndc(clipCoord.x() / clipCoord.w(), clipCoord.y() / clipCoord.w(), clipCoord.z() / clipCoord.w());
+
+    float winX = viewport.x() + viewport.width() * (ndc.x() + 1.0) / 2.0;
+    float winY = viewport.y() + viewport.height() * (1.0 - (ndc.y() + 1.0) / 2.0); // Y is inverted
+
+    return QVector3D(winX, winY, (ndc.z() + 1.0) / 2.0);
+}
+
+void ViewportWidget::drawAxisLabels(QPainter& painter, const QMatrix4x4& modelView, const QMatrix4x4& projection)
+{
+    painter.setPen(Qt::white);
+    painter.setFont(QFont("Arial", 10));
+
+    const int range = 50;
+    const int step = 5;
+
+    auto drawLabelsForAxis = [&](int axis_idx) {
+        for (int i = -range; i <= range; i += step) {
+            if (i == 0) continue;
+            QVector3D worldCoord;
+            worldCoord[axis_idx] = i;
+
+            QVector3D screenPos = project(worldCoord, modelView, projection, rect());
+            if (screenPos.z() < 1.0f) { // Not clipped
+                painter.drawText(screenPos.toPoint(), QString::number(i));
+            }
+        }
+    };
+
+    if (m_currentPlane == SketchPlane::XY) {
+        drawLabelsForAxis(0); // X
+        drawLabelsForAxis(1); // Y
+    } else if (m_currentPlane == SketchPlane::XZ) {
+        drawLabelsForAxis(0); // X
+        drawLabelsForAxis(2); // Z
+    } else if (m_currentPlane == SketchPlane::YZ) {
+        drawLabelsForAxis(1); // Y
+        drawLabelsForAxis(2); // Z
+    }
+}