feat: Implement dynamic sketch grid based on camera zoom

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

src/SketchGrid.cpp

@@ -1,11 +1,35 @@
 #include "SketchGrid.h"
 #include "ViewportWidget.h"
+#include "Camera.h"
 #include <QOpenGLContext>
 #include <QOpenGLExtraFunctions>
 #include <QOpenGLShaderProgram>
 #include <QPainter>
 #include <QVector>
 
+namespace {
+struct GridParams {
+    float minorIncrement;
+    float majorIncrement;
+    int gridSize;
+};
+
+GridParams getGridParams(float zoom)
+{
+    if (zoom > 8.0f) {
+        return { 0.2f, 1.0f, 10 };
+    } else if (zoom > 2.0f) {
+        return { 1.0f, 5.0f, 50 };
+    } else if (zoom > 0.8f) {
+        return { 5.0f, 25.0f, 250 };
+    } else if (zoom > 0.4f) {
+        return { 10.0f, 50.0f, 500 };
+    } else {
+        return { 20.0f, 100.0f, 1000 };
+    }
+}
+} // namespace
+
 SketchGrid::SketchGrid(ViewportWidget* viewport) : m_viewport(viewport)
 {
 }
@@ -48,23 +72,29 @@ void SketchGrid::paintGL(SketchPlane plane, QOpenGLShaderProgram* shaderProgram,
 
 void SketchGrid::drawGridLines(SketchPlane plane, QOpenGLShaderProgram* shaderProgram, int colorLoc)
 {
-    const int gridSize = 50;
+    auto params = getGridParams(m_viewport->camera()->zoom());
+    const float minorIncrement = params.minorIncrement;
+    const int gridSize = params.gridSize;
+
     QVector<GLfloat> minorLines;
     QVector<GLfloat> majorLines;
 
-    for (int i = -gridSize; i <= gridSize; ++i)
+    int numLines = gridSize / minorIncrement;
-    {
+    for (int i = -numLines; i <= numLines; ++i) {
-        if (i == 0) continue;
+        if (i == 0)
+            continue;
+
+        float pos = i * minorIncrement;
         QVector<GLfloat>& current_vector = (i % 5 == 0) ? majorLines : minorLines;
         if (plane == XY) {
-            current_vector << i << 0 << -gridSize << i << 0 << gridSize;
+            current_vector << pos << 0 << -gridSize << pos << 0 << gridSize;
-            current_vector << -gridSize << 0 << i << gridSize << 0 << i;
+            current_vector << -gridSize << 0 << pos << gridSize << 0 << pos;
         } else if (plane == XZ) {
-            current_vector << i << -gridSize << 0 << i << gridSize << 0;
+            current_vector << pos << -gridSize << 0 << pos << gridSize << 0;
-            current_vector << -gridSize << i << 0 << gridSize << i << 0;
+            current_vector << -gridSize << pos << 0 << gridSize << pos << 0;
         } else { // YZ
-            current_vector << 0 << i << -gridSize << 0 << i << gridSize;
+            current_vector << 0 << pos << -gridSize << 0 << pos << gridSize;
-            current_vector << 0 << -gridSize << i << 0 << gridSize << i;
+            current_vector << 0 << -gridSize << pos << 0 << gridSize << pos;
         }
     }
 
@@ -130,18 +160,23 @@ void SketchGrid::paintAxisLabels(QPainter& painter, SketchGrid::SketchPlane plan
     painter.setPen(Qt::white);
     painter.setFont(QFont("Arial", 10));
 
-    const int range = 50;
+    auto params = getGridParams(m_viewport->camera()->zoom());
-    const int step = 5;
+    const float majorIncrement = params.majorIncrement;
+    const int range = params.gridSize;
 
     auto drawLabelsForAxis = [&](int axis_idx) {
-        for (int i = -range; i <= range; i += step) {
+        int numLabels = range / majorIncrement;
-            if (i == 0) continue;
+        for (int i = -numLabels; i <= numLabels; ++i) {
+            if (i == 0)
+                continue;
+
+            float val = i * majorIncrement;
             QVector3D worldCoord;
-            worldCoord[axis_idx] = i;
+            worldCoord[axis_idx] = val;
 
             QVector3D screenPos = m_viewport->project(worldCoord, modelView, projection, m_viewport->rect());
             if (screenPos.z() < 1.0f) { // Not clipped
-                painter.drawText(screenPos.toPoint(), QString::number(i));
+                painter.drawText(screenPos.toPoint(), QString::number(val));
             }
         }
     };