Graph/scatterplot improvements (#893)

* many graph/scatterplot fixes: 722, 882, 758, 886

* fix e2e test breakage caused by graph transform work

* convert webgl point shaders to use flags rather than explicit point size

* remove unused packages from dependencies

* fix typo in regl prop name

* factor common code into util helper file

* legibility tweaks

client/src/components/scatterplot/drawPointsRegl.js

@@ -1,44 +1,62 @@
-// jshint esversion: 6
-const mat4 = require("gl-mat4");
-
-// opacity: https://github.com/spacetx/starfish/blob/master/viz/draw/regions.js
+import { glPointFlags } from "../../util/glHelpers";
 
 export default function(regl) {
   return regl({
     vert: `
     precision mediump float;
+
     attribute vec2 position;
     attribute vec3 color;
-    attribute float size;
-    uniform float distance;
-    uniform mat4 projection, view;
-    varying vec3 fragColor;
+    attribute float flag;
+
+    uniform mat3 projection;
+    uniform float nPoints;
+    uniform float minViewportDimension;
+
+    varying vec4 fragColor;
+
+    const float zBottom = 0.99;
+    const float zMiddle = 0.;
+    const float zTop = -1.;
+
+    // import getFlags()
+    ${glPointFlags}
+
     void main() {
-      gl_PointSize = 7.0 / pow(distance, 2.5) + size;
-      gl_Position = projection * view * vec4(position.x, -position.y, 0, 1);
-      fragColor = color;
+      bool isNaN, isSelected, isHighlight;
+      getFlags(flag, isNaN, isSelected, isHighlight);
+
+      float size = isHighlight ? 8. : isSelected ? 4. : 1.;
+      gl_PointSize = size;
+
+      float z = isNaN ? zBottom : (isHighlight ? zTop : zMiddle);
+      vec3 xy = projection * vec3(position, 1.);
+      gl_Position = vec4(xy.xy, z, 1.);
+
+      float alpha = isNaN ? 0.9 : 1.0;
+      fragColor = vec4(color, alpha);
     }`,
 
     frag: `
     precision mediump float;
-    varying vec3 fragColor;
+    varying vec4 fragColor;
     void main() {
       if (length(gl_PointCoord.xy - 0.5) > 0.5) {
         discard;
       }
-      gl_FragColor = vec4(fragColor, 1);
+      gl_FragColor = fragColor;
     }`,
 
     attributes: {
       position: regl.prop("position"),
       color: regl.prop("color"),
-      size: regl.prop("size")
+      flag: regl.prop("flag")
     },
 
     uniforms: {
-      distance: regl.prop("distance"),
-      view: regl.prop("view"),
-      projection: () => mat4.perspective([], Math.PI / 2, 1, 0.01, 1000)
+      projection: regl.prop("projection"),
+      nPoints: regl.prop("nPoints"),
+      minViewportDimension: regl.prop("minViewportDimension")
     },
 
     count: regl.prop("count"),