qgspointcloud3dsymbol: Add support for gl_ClipDistance

This is achieved with two changes:
1. define the plane equation as uniform with the
`Qgs3DUtils::addBoundingBoxParametersToEffect` call
2. include `clipplane.inc` file in the vertex shader file and call
setClipDistance()

With these changes, the planes defined in the framegraph are used.

src/3d/shaders/pointcloud.vert

@@ -23,6 +23,8 @@ out vec3 pointColor;
 out vec3 worldPosition; //used when points are triangulated
 out vec3 vertNorm; //used when points are triangulated
 
+#pragma include clipplane.inc
+
 void main(void)
 {
     gl_Position = modelViewProjection * vec4(vertexPosition, 1);
@@ -49,4 +51,6 @@ void main(void)
       classParameter = int(vertexParameter);
       break;
     }
+
+    setClipDistance(worldPosition);
 }

src/3d/symbols/qgspointcloud3dsymbol_p.cpp

@@ -24,6 +24,7 @@
 #include "qgspointcloudindex.h"
 #include "qgspointcloudblockrequest.h"
 #include "qgsfeedback.h"
+#include "qgs3dutils.h"
 
 #include <Qt3DRender/QGeometryRenderer>
 #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
@@ -316,6 +317,7 @@ void QgsPointCloud3DSymbolHandler::makeEntity( Qt3DCore::QEntity *parent, const
   technique->addParameter( new Qt3DRender::QParameter( "triangulate", !out.triangles.isEmpty() ) );
 
   Qt3DRender::QEffect *eff = new Qt3DRender::QEffect;
+  Qgs3DUtils::addBoundingBoxParametersToEffect( eff, context.map() );
   eff->addTechnique( technique );
   mat->setEffect( eff );