Adapted Escape the Dawn engine.

src/Shaders/VisualizeDepth.frag.glsl

@@ -0,0 +1,24 @@
+#version 430
+
+layout(binding = 0) uniform sampler2D DepthTexture;
+
+in VertexData {
+	vec3 Position;
+	vec2 TextureCoord;
+} Input;
+
+out vec4 FragmentColor;
+
+float LinearizeDepth(float z)
+{
+  float n = 0.1; // camera z near
+  float f = 800.0; // camera z far
+  return (2.0 * n) / (f + n - z * (f - n));	
+}
+
+void main() {
+	float z = texture(DepthTexture, Input.TextureCoord).x;
+	vec4 color = vec4(z, z, z, 0);
+
+	FragmentColor = color;
+}