duplicate drawPoints file for scatterplot, from graph

src/components/scatterplot/drawPointsRegl.js

@@ -0,0 +1,55 @@
+const mat4 = require('gl-mat4')
+
+// opacity: https://github.com/spacetx/starfish/blob/master/viz/draw/regions.js
+
+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;
+    void main() {
+      gl_PointSize = 7.0 / pow(distance, 2.5) + size;
+      gl_Position = projection * view * vec4(position.x, -position.y, 0, 1);
+      fragColor = color;
+    }`,
+
+    frag: `
+    precision mediump float;
+    varying vec3 fragColor;
+    void main() {
+      if (length(gl_PointCoord.xy - 0.5) > 0.5) {
+        discard;
+      }
+      gl_FragColor = vec4(fragColor, 1);
+    }`,
+
+    attributes: {
+      position: regl.prop('position'),
+      color: regl.prop('color'),
+      size: regl.prop('size')
+    },
+
+    uniforms: {
+      distance: regl.prop('distance'),
+      view: regl.prop('view'),
+      projection: (context, props) => {
+        return mat4.perspective(
+          [],
+          Math.PI / 2,
+          context.viewportWidth * props.scale / context.viewportHeight,
+          0.01,
+          1000
+        )
+      },
+    },
+
+    count: regl.prop('count'),
+
+    primitive: 'points'
+  })
+}