Enhancements to breadcrumb trail

trailshader.glsl

@@ -1,8 +1,10 @@
-#version 460 core
-// Simple vertex shader for the player's breadcrumb trail triangles.
+#version 330 core
+// Dynamic ribbon trail vertex shader. Timestamp is used by the fragment shader
+// to fade recent path segments from red toward brown as they age.
 layout (location = 0) in vec3 aPos;
+layout (location = 1) in float aTimestamp;
 
-out vec3 FragPos;
+out float TrailTimestamp;
 
 uniform mat4 model;
 uniform mat4 view;
@@ -10,7 +12,7 @@ uniform mat4 projection;
 
 void main()
 {
-    FragPos = vec3(model * vec4(aPos, 1.0));
+    TrailTimestamp = aTimestamp;
 
-    gl_Position = projection * view * vec4(FragPos, 1.0);
+    gl_Position = projection * view * model * vec4(aPos, 1.0);
 }