Added toggle-able section line highlighting

resources/shaders/heightmap0.frag

@@ -3,9 +3,15 @@ out vec4 FragColor;
 
 in vec4 vertexColor;
 in float colorCoord;
+in int colorOverridden;
 
 uniform sampler1D colorscheme;
 
 void main(){
-	FragColor = texture(colorscheme, colorCoord);
-}
+  if(colorOverridden == 1){
+    FragColor = vertexColor;
\ No newline at end of file
+  }
+  else{
+    FragColor = texture(colorscheme, colorCoord);
+  }
+}

resources/shaders/heightmap0.vert

@@ -3,6 +3,7 @@ layout (location = 0) in vec3 aPos;
 
 out vec4 vertexColor;
 out float colorCoord;
+out int colorOverridden;
 
 //perspective related uniforms
 uniform mat4 model;
@@ -15,6 +16,14 @@ uniform float minZ;
 uniform float maxZ;
 uniform float bad_z_value;
 
+//Cross section plots lines related uniforms
+uniform int plotLinesEnabled;
+uniform vec3 plotLineAlongX_color;
+uniform vec3 plotLineAlongY_color;
+uniform float plotLineAlongX_y;
+uniform float plotLineAlongY_x;
+uniform float plotLineHalfThickness;
+
 void main(){
 	vec3 position = aPos;
 	if(aPos.z != bad_z_value){
@@ -26,6 +35,19 @@ void main(){
 		position.z = minZ - 0.5 * scale * (maxZ - minZ);
 	}
 	gl_Position = projection * view * model * vec4(position, 1.0);
-	vertexColor = vec4(position.z, 0.0, 0.0, 1.);
 	colorCoord = (aPos.z - minZ)/(maxZ-minZ);
-}
+	vertexColor = vec4(position.z, 0.0, 0.0, 1.);
\ No newline at end of file
+  colorOverridden = 0;
+
+  //Check if on cross section line
+  if(plotLinesEnabled == 1){
+    if(abs(position.x - plotLineAlongY_x) < plotLineHalfThickness){
+      colorOverridden = 1;
+      vertexColor = vec4(plotLineAlongY_color, 1.);
+    }
+    else if(abs(position.y - plotLineAlongX_y) < plotLineHalfThickness){
+      colorOverridden = 1;
+      vertexColor = vec4(plotLineAlongX_color, 1.);
+    }
+  }
+}