Runtime selectible line width

CHANGELOG

@@ -9,6 +9,19 @@
                              https://glvis.org
 
 
+Version 4.5.1 (development)
+===========================
+- Added configurable line width for mesh edges and element boundaries when MSAA
+  is enabled. Line width can be adjusted at runtime using ';' (decrease) and '''
+  (increase) keys in 0.25 pixel increments (minimum 0.25, no maximum). Default
+  line width now is 1.5 pixels.
+
+- Without antialiasing, the original GL_LINES rendering is still used. With
+  antialiasing, lines are rendered using shader-expanded triangles and hardware
+  MSAA with fragment shader techniques. The line rendering format switches
+  automatically when toggling MSAA with the 'A' key.
+
+
 Version 4.5 released on Feb 6, 2026
 ===================================
 

README.md

@@ -171,6 +171,7 @@ Key commands
 - <kbd>*</kbd> / <kbd>/</kbd> – Zoom in/out
 - <kbd>+</kbd> / <kbd>-</kbd> – Stretch/compress in `z`-direction
 - <kbd>[</kbd> / <kbd>]</kbd> – Shrink/enlarge the bounding box (relative to the colorbar)
+- <kbd>;</kbd> / <kbd>'</kbd> – Decrease/increase line width
 - <kbd>(</kbd> / <kbd>)</kbd> – Shrink/enlarge the visualization window
 - <kbd>.</kbd> – Start/stop `z`-spinning (speed/direction can be controlled with <kbd>0</kbd> / <kbd>Enter</kbd>)
 - <kbd>←</kbd>, <kbd>→</kbd>, <kbd>↑</kbd>, <kbd>↓</kbd> – Manual rotation

lib/aux_vis.cpp

@@ -258,6 +258,8 @@ GLWindow* InitVisualization(const char name[], int x, int y, int w, int h,
 
    wnd->setOnKeyDown (SDLK_LEFTBRACKET, ScaleDown);
    wnd->setOnKeyDown (SDLK_RIGHTBRACKET, ScaleUp);
+   wnd->setOnKeyDown (SDLK_SEMICOLON, DecreaseLineWidth);
+   wnd->setOnKeyDown (SDLK_QUOTE, IncreaseLineWidth);
    wnd->setOnKeyDown (SDLK_AT, LookAt);
 
 #ifndef __EMSCRIPTEN__
@@ -1650,6 +1652,26 @@ void ScaleDown()
    SendExposeEvent();
 }
 
+void IncreaseLineWidth()
+{
+   float new_w = GetLineWidth() + 0.25f;
+   float new_w_aa = GetLineWidthMS() + 0.25f;
+   SetLineWidth(new_w);
+   SetLineWidthMS(new_w_aa);
+   cout << "Line width: " << new_w << " (antialiased: " << new_w_aa << ")" << endl;
+   SendExposeEvent();
+}
+
+void DecreaseLineWidth()
+{
+   float new_w = std::max(0.25f, GetLineWidth() - 0.25f);
+   float new_w_aa = std::max(0.25f, GetLineWidthMS() - 0.25f);
+   SetLineWidth(new_w);
+   SetLineWidthMS(new_w_aa);
+   cout << "Line width: " << new_w << " (antialiased: " << new_w_aa << ")" << endl;
+   SendExposeEvent();
+}
+
 void LookAt()
 {
    cout << "ViewCenter = (" << locscene->ViewCenterX << ','

lib/aux_vis.hpp

@@ -104,6 +104,8 @@ void ScaleDown();
 void LookAt();
 void ShrinkWindow();
 void EnlargeWindow();
+void IncreaseLineWidth();
+void DecreaseLineWidth();
 void MoveResizeWindow(int x, int y, int w, int h);
 void ResizeWindow(int w, int h);
 void SetWindowTitle(const char *title);

lib/gl/renderer.cpp

@@ -49,6 +49,11 @@ void MeshRenderer::setAntialiasing(bool aa_status)
    if (msaa_enable != aa_status)
    {
       msaa_enable = aa_status;
+      // Update device's MSAA state for conditional line rendering
+      if (device)
+      {
+         device->setMSAAEnabled(aa_status);
+      }
       if (msaa_enable)
       {
          if (!feat_use_fbo_antialias)
@@ -398,6 +403,9 @@ void MeshRenderer::buffer(GlDrawable* buf)
 
 void GLDevice::init()
 {
+   // Initialize line width
+   line_w = 1.0f;
+   msaa_enabled = false;
    // enable depth testing
    glDepthFunc(GL_LEQUAL);
    glEnable(GL_DEPTH_TEST);

lib/gl/renderer.hpp

@@ -100,6 +100,9 @@ class GLDevice
 
    std::array<float, 4> static_color;
 
+   float line_w;
+   bool msaa_enabled;
+
 protected:
    resource::TextureHandle passthrough_texture;
 
@@ -135,7 +138,9 @@ class GLDevice
    void disableBlend() { glDisable(GL_BLEND); }
    void enableDepthWrite() { glDepthMask(GL_TRUE); }
    void disableDepthWrite() { glDepthMask(GL_FALSE); }
-   void setLineWidth(float w) { glLineWidth(w); }
+   void setLineWidth(float w) { line_w = w; glLineWidth(w); }
+   // Update MSAA state for conditional line rendering
+   void setMSAAEnabled(bool enabled) { msaa_enabled = enabled; }
 
    virtual void init();
    virtual DeviceType getType() = 0;
@@ -195,6 +200,8 @@ class MeshRenderer
    bool msaa_enable;
    int msaa_samples;
    GLuint color_tex, alpha_tex, font_tex;
+   // Separate line widths for non-MSAA (line_w) and MSAA (line_w_aa) modes
+   // Allows different defaults: 1.0 for GL_LINES, 1.5 for shader-expanded
    float line_w, line_w_aa;
    PaletteState* palette;
 
@@ -213,7 +220,8 @@ class MeshRenderer
       device.reset(new TDevice());
       device->setLineWidth(line_w);
       device->init();
-      msaa_enable = false;
+      // Synchronize device's MSAA state with renderer's state
+      device->setMSAAEnabled(msaa_enable);
    }
 
    template<typename TDevice>
@@ -248,8 +256,10 @@ class MeshRenderer
    }
    int getSamplesMSAA() { return msaa_samples; }
 
+   // Line width for non-MSAA mode (GL_LINES)
    void setLineWidth(float w);
    float getLineWidth() { return line_w; }
+   // Line width for MSAA mode (shader-expanded triangles)
    void setLineWidthMS(float w);
    float getLineWidthMS() { return line_w_aa; }