First working pass of Waveform

Remove the sum, add some commments, and
make it scale to the full window.

TODO:
 * Hook up CM.
 * Add UI for intensity
 * Add lines at 20% increments, plus under /
    overshoot?
 * Add UI for increments.

app/shaders/rgbwaveform.frag

@@ -6,8 +6,6 @@
 uniform sampler2D ove_maintex;
 uniform vec2 ove_resolution;
 uniform vec2 ove_viewport;
-varying vec2 ove_texcoord;
-
 
 uniform float threshold;
 
@@ -17,10 +15,21 @@ out vec4 fragColor;
 
 void main(void) {
     vec3 col = vec3(0.0);
-    float increment = 1.0 / 255.0;
+    // Set an increment default to 10 bit encodings. This would likely be
+    // better served as a UI control, as waveforms will change their combing
+    // based on how granular the increment is set. For example, it can be
+    // challenging to spot 8 bit combing with an increment of 1. / 2.^8 - 1.
+    float increment = 1.0 / (pow(2, 10) - 1.0);
     float maxb = ove_texcoord.y + increment;
     float minb = ove_texcoord.y - increment;
 
+    // Intensity would make sense to also expose via the UI, as a density
+    // slider allows you to peek past certain values or reveal very low
+    // values. Hard coding it for now, as there isn't a clear way to have
+    // the various bit depth / code values always display at a consistent
+    // emission output strength.
+    float intensity = 0.10;
+
     int y_lim = int(ove_resolution.y);
 
     vec3 cur_col = vec3(0.0);
@@ -31,10 +40,18 @@ void main(void) {
         ).rgb;
 
         col += step(vec3(ove_texcoord.y - increment), cur_col) *
-            step(cur_col, vec3(ove_texcoord.y + increment));
+            step(cur_col, vec3(ove_texcoord.y + increment)) * intensity;
+
+        // TODO: Implement proper luma / luminance based values.
+        // This is simply taking the luminance weights derived from the
+        // OCIO configuration or the RGB to XYZ matrix and multiplying
+        // the above step approach by the luminance weights.
+        // EG:
+        // cur_lum = cur_col * lum_coeffs;
+        //
+        // col += step(vec3(ove_texcoord.y - increment), cur_lum) *
+        //     step(cur_lum, vec3(ove_texcoord.y + increment));
 
-        //float l = dot(x, x);
-        //col += step(l, maxb*maxb)*step(minb*minb, l) / (ove_resolution.y * 0.125);
     }
 
     gl_FragColor = vec4(col, 1.0);