allow circles to be clipped against a plane

allen-cell-animated · Mar 18, 2024 · 17ee71d · 17ee71d
1 parent 23592c4
commit 17ee71d
Show file tree

Hide file tree

Showing 3 changed files with 18 additions and 7 deletions.
diff --git a/renderlib/RotateTool.cpp b/renderlib/RotateTool.cpp
@@ -261,6 +261,8 @@ RotateTool::draw(SceneView& scene, Gesture& gesture)
 
   gesture.graphics.addCommand(GL_LINES);
 
+  glm::vec4 discPlane(camFrame.vz, -glm::dot(camFrame.vz, axis.p));
+
   float axisscale = scale * 0.85f;
   // Draw the x ring in yz plane
   {
@@ -269,7 +271,7 @@ RotateTool::draw(SceneView& scene, Gesture& gesture)
     if (m_activeCode == RotateTool::kRotateX) {
       color = glm::vec3(1, 1, 0);
     }
-    gesture.drawCircle(axis.p, axis.l.vy * axisscale, axis.l.vz * axisscale, 48, color, 1, code);
+    gesture.drawCircle(axis.p, axis.l.vy * axisscale, axis.l.vz * axisscale, 48, color, 1, code, &discPlane);
   }
   // Draw the y ring in xz plane
   {
@@ -278,7 +280,7 @@ RotateTool::draw(SceneView& scene, Gesture& gesture)
     if (m_activeCode == RotateTool::kRotateY) {
       color = glm::vec3(1, 1, 0);
     }
-    gesture.drawCircle(axis.p, axis.l.vz * axisscale, axis.l.vx * axisscale, 48, color, 1, code);
+    gesture.drawCircle(axis.p, axis.l.vz * axisscale, axis.l.vx * axisscale, 48, color, 1, code, &discPlane);
   }
   // Draw the z ring in xy plane
   {
@@ -287,7 +289,7 @@ RotateTool::draw(SceneView& scene, Gesture& gesture)
     if (m_activeCode == RotateTool::kRotateZ) {
       color = glm::vec3(1, 1, 0);
     }
-    gesture.drawCircle(axis.p, axis.l.vx * axisscale, axis.l.vy * axisscale, 48, color, 1, code);
+    gesture.drawCircle(axis.p, axis.l.vx * axisscale, axis.l.vy * axisscale, 48, color, 1, code, &discPlane);
   }
 
   // Draw the camera-axis rotation manipulator as a circle always facing the view

diff --git a/renderlib/gesture/gesture.cpp b/renderlib/gesture/gesture.cpp
@@ -616,7 +616,8 @@ Gesture::drawCircle(glm::vec3 center,
                     uint32_t numSegments,
                     glm::vec3 color,
                     float opacity,
-                    uint32_t code)
+                    uint32_t code,
+                    glm::vec4* clipPlane)
 {
   for (int i = 0; i < numSegments; ++i) {
     float t0 = float(i) / float(numSegments);
@@ -628,8 +629,15 @@ Gesture::drawCircle(glm::vec3 center,
     glm::vec3 p0 = center + xaxis * cosf(theta0) + yaxis * sinf(theta0);
     glm::vec3 p1 = center + xaxis * cosf(theta1) + yaxis * sinf(theta1);
 
-    graphics.addLine(Gesture::Graphics::VertsCode(p0, color, opacity, code),
-                     Gesture::Graphics::VertsCode(p1, color, opacity, code));
+    if (clipPlane) {
+      if (glm::dot(*clipPlane, glm::vec4(p0, 1.0)) > 0 && glm::dot(*clipPlane, glm::vec4(p1, 1.0)) > 0) {
+        graphics.addLine(Gesture::Graphics::VertsCode(p0, color, opacity, code),
+                         Gesture::Graphics::VertsCode(p1, color, opacity, code));
+      }
+    } else {
+      graphics.addLine(Gesture::Graphics::VertsCode(p0, color, opacity, code),
+                       Gesture::Graphics::VertsCode(p1, color, opacity, code));
+    }
   }
 }
 

diff --git a/renderlib/gesture/gesture.h b/renderlib/gesture/gesture.h
@@ -424,7 +424,8 @@ struct Gesture
                   uint32_t numSegments,
                   glm::vec3 color,
                   float opacity,
-                  uint32_t code);
+                  uint32_t code,
+                  glm::vec4* clipPlane = nullptr);
 
   // does not draw a flat base
   void drawCone(glm::vec3 base,