Draft: Added setShader to CurveArtist

Demos/Shaders/Line_Pulse_Thickness.frag

@@ -0,0 +1,29 @@
+// FRAGMENT SHADER
+// Creates a pulsing intensity effect that simulates line thickness variation
+
+// Use GLSL 1.20 (OpenGL 2.1)
+#version 120
+
+uniform float osg_FrameTime;     // From OSG
+varying float vertexLocation;    // From vertex shader (alternates 0/1 for line endpoints)
+
+const float pulseSpeed = 2.0;      // Speed of pulsing (higher = faster)
+const float minIntensity = 0.4;    // Minimum brightness (0-1)
+const float maxIntensity = 1.0;    // Maximum brightness (0-1)
+
+void main(void)
+{
+  vec4 baseColor = gl_Color;
+
+  // Create smooth pulsing wave using sine
+  float pulse = sin(osg_FrameTime * pulseSpeed) * 0.5 + 0.5; // 0 to 1
+
+  // Scale pulse between min and max intensity
+  float intensity = mix(minIntensity, maxIntensity, pulse);
+
+  // Apply intensity to color and alpha for a "glowing" pulse effect
+  vec4 finalColor = baseColor * intensity;
+  finalColor.a = baseColor.a * intensity; // Also pulse the alpha
+
+  gl_FragColor = finalColor;
+}

Demos/Shaders/Line_Pulse_Traveling.frag

@@ -0,0 +1,31 @@
+// FRAGMENT SHADER
+// Draws a pulse that travels from the start of the trajectory to the end
+
+// Use GLSL 1.20 (OpenGL 2.1)
+#version 120
+
+uniform float osg_FrameTime;      // From OSG
+uniform float of_NumVertices;     // Total vertex count, set by CurveArtist
+varying float vertexRawID;        // Raw vertex index from vertex shader
+
+const float pulseDuration = 2.0;  // Seconds for one full pass along the line
+const float pulseWidth = 0.05;    // Width of pulse as fraction of total line length
+
+void main(void)
+{
+  vec4 color = gl_Color;
+  vec4 colorInv = vec4(1.0 - gl_Color.rgb, 1.0);
+
+  // Normalize vertex index to [0, 1] over the full line
+  float linePos = vertexRawID / max(of_NumVertices - 1.0, 1.0);
+
+  // Pulse center travels from 0 (start) to 1 (end) over pulseDuration seconds
+  float pulseCenter = fract(osg_FrameTime / pulseDuration);
+
+  // Create a smooth 0-1-0 bump centered at the pulse location
+  float y1 = smoothstep(pulseCenter - pulseWidth, pulseCenter, linePos);
+  float y2 = smoothstep(pulseCenter, pulseCenter + pulseWidth, linePos);
+  float pulseVal = y1 - y2;
+
+  gl_FragColor = mix(color, colorInv, pulseVal);
+}

include/OpenFrames/CurveArtist.hpp

@@ -67,6 +67,7 @@ namespace OpenFrames
     void setColor(float r, float g, float b);
     void setWidth(float width);
     void setPattern(GLint factor, GLushort pattern);
+    bool setShader(const std::string &fname);
 
     /** Data was cleared from or added to the trajectory. Inherited
         from TrajectoryArtist */
@@ -88,6 +89,7 @@ namespace OpenFrames
     osg::ref_ptr<osg::LineWidth> _lineWidth;
     osg::ref_ptr<osg::LineStipple>  _linePattern;
     osg::ref_ptr<osg::Vec4Array> _lineColors;
+    osg::ref_ptr<osg::Shader> _fragShader; // Line fragment shader
 
     mutable bool _dataValid; // If trajectory supports required data
     mutable bool _dataZero; // If we are just drawing at the origin

include/OpenFrames/OF_Interface.h

@@ -1768,6 +1768,17 @@ OF_EXPORT void OF_FCN(ofcurveartist_setwidth)(float *width);
 */
 OF_EXPORT void OF_FCN(ofcurveartist_setpattern)(int *factor, unsigned short *pattern);
 
+/*
+ * \brief Set GLSL fragment shader used to draw the curve, overriding any existing shader.
+ *
+ * If an empty string is provided, the shader is reset to default.
+ *
+ * This applies to the current active CurveArtist.
+ *
+ * \param fname File containing the shader source.
+ */
+OF_EXPORT void OF_FCN(ofcurveartist_setshader)(OF_CHARARG(fname));
+
 /*****************************************************************
 	SegmentArtist Functions
 A SegmentArtist is a type of TrajectoryArtist that allows arbitrary

src/CurveArtist.cpp

@@ -21,6 +21,10 @@
 #include <OpenFrames/CurveArtist.hpp>
 #include <OpenFrames/DoubleSingleUtils.hpp>
 #include <osg/Geometry>
+#include <osg/Shader>
+#include <osg/Program>
+#include <osgDB/FileUtils>
+#include <osgDB/ReadFile>
 #include <climits>
 
 namespace OpenFrames
@@ -108,6 +112,10 @@ class CurveArtistUpdateCallback : public osg::Callback
       _vertexLow->dirty();
     }
 
+    // Keep of_NumVertices uniform in sync so traveling-pulse shaders know the line length
+    osg::Uniform* numVertsUniform = _ca->getOrCreateStateSet()->getUniform("of_NumVertices");
+    if(numVertsUniform) numVertsUniform->set((float)_drawArrays->getCount());
+
     // Continue traversing as needed
     return traverse(object, data);
   }
@@ -205,6 +213,12 @@ CurveArtist::CurveArtist(const Trajectory *traj)
 	stateset->setAttribute(_lineWidth.get());
 	stateset->setAttributeAndModes(_linePattern.get());
 
+  // Initialize shader for custom line effects (optional, added to program on demand)
+  _fragShader = new osg::Shader(osg::Shader::FRAGMENT);
+
+  // Uniform holding total vertex count; used by traveling-pulse shaders
+  stateset->addUniform(new osg::Uniform("of_NumVertices", 0.0f));
+
   // Initialize colors
   // Currently we use one color for the whole trajectory, but this can be
   // changed later for per-vertex colors
@@ -296,6 +310,35 @@ void CurveArtist::setPattern( GLint factor, GLushort pattern )
 	_linePattern->setPattern(pattern);
 }
 
+bool CurveArtist::setShader(const std::string &fname)
+{
+  // Remove shader if empty filename
+  if(fname.length() == 0)
+  {
+    _program->removeShader(_fragShader);
+    return true;
+  }
+
+  // Load shader source from file using the non-deprecated osgDB API
+  osg::ref_ptr<osg::Shader> tmpShader = osgDB::readRefShaderFile(osg::Shader::FRAGMENT, fname);
+  if(!tmpShader.valid())
+  {
+    OSG_WARN << "OpenFrames::CurveArtist ERROR: Shader file \'" << fname << "\' not properly loaded!" << std::endl;
+    return false;
+  }
+  _fragShader->setShaderSource(tmpShader->getShaderSource());
+
+  // Re-attach shader to program if it was previously removed
+  bool attached = false;
+  for(unsigned int i = 0; i < _program->getNumShaders(); ++i)
+  {
+    if(_program->getShader(i) == _fragShader.get()) { attached = true; break; }
+  }
+  if(!attached) _program->addShader(_fragShader);
+
+  return true;
+}
+
 void CurveArtist::dataCleared(const Trajectory* traj)
 {
 	verifyData();

src/OF_Interface.cpp

@@ -2549,6 +2549,19 @@ void OF_FCN(ofcurveartist_setpattern)(int *factor, unsigned short *pattern)
     }
 }
 
+OF_EXPORT void OF_FCN(ofcurveartist_setshader)(OF_CHARARG(fname))
+{
+	CurveArtist *artist = dynamic_cast<CurveArtist*>(_objs->_currArtist);
+    if (artist) {
+      // Convert given character string and length to a proper C string
+      std::string temp(OF_STRING(fname));
+      _objs->_intVal = !artist->setShader(temp);
+    }
+    else {
+      _objs->_intVal = -2;
+    }
+}
+
 /************************************************
 	SegmentArtist Functions
 ************************************************/

src/OpenFrames.f90

@@ -902,6 +902,11 @@ SUBROUTINE ofcurveartist_setpattern(factor, pattern)
 	INTEGER(2), INTENT(IN) :: pattern
 	END SUBROUTINE
 
+	SUBROUTINE ofcurveartist_setshader(fname)
+	!DEC$ ATTRIBUTES DLLIMPORT,C,REFERENCE :: ofcurveartist_setshader
+	CHARACTER(LEN=*), INTENT(IN) :: fname
+	END SUBROUTINE
+
 ! SegmentArtist functions
 
 	SUBROUTINE ofsegmentartist_create(name)

src/TrajectoryArtist.cpp

@@ -27,6 +27,7 @@ namespace OpenFrames
 // Implement vertex shader for Rendering Relative to Eye using GPU
 static const char *OFTA_VertSource = {
   "#version 120\n"
+  "#extension GL_EXT_gpu_shader4 : enable\n" // Enables gl_VertexID
   "uniform mat4 osg_ProjectionMatrix;\n"
 
   // ModelView matrix with zero translation component
@@ -40,6 +41,13 @@ static const char *OFTA_VertSource = {
   // High part comes in through gl_Vertex
   "attribute vec4 of_VertexLow;\n"
 
+  // Vertex location along line (0 or 1 for alternating vertices)
+  // Used by custom shaders like Line_Pulse.frag
+  "varying float vertexLocation;\n"
+
+  // Raw vertex index, used with of_NumVertices uniform for full-line position
+  "varying float vertexRawID;\n"
+
   "void main(void)\n"
   "{\n"
      // Low part of vertex - eye and associated numerical error
@@ -57,6 +65,10 @@ static const char *OFTA_VertSource = {
   "  gl_Position = osg_ProjectionMatrix*of_RTEModelViewMatrix*vec4(diffHigh+diffLow, 1.0);\n"
   "  gl_FrontColor = gl_Color;\n"
   "  gl_TexCoord[0] = gl_MultiTexCoord0;\n"
+
+     // Compute vertex location for line shaders (0 or 1 for alternating vertices)
+  "  vertexLocation = mod(float(gl_VertexID), 2.0);\n"
+  "  vertexRawID = float(gl_VertexID);\n"
   "}\n"
 };