message: allow radius parameter for upsample bloom stage
  The original article we used for our bloom (siggraph'14) called for
  a radius parameter for the upsample stage. We're always using 1.0 right
  now, but it is useful to keep this possibility for experimentations.
diff: @@ -31,6 +31,8 @@ vertex {
  }
  fragment {
  + void dummy(){}
  +
  void postProcess(inout PostProcessInputs postProcess) {
  float lod = materialParams.level;
  highp vec2 uv = variable_vertex.xy;
  @@ -44,16 +46,21 @@ fragment {
  c += textureLod(materialParams_source, uv + d.zy, lod).rgb;
  postProcess.color.rgb = c * 0.25;
  #else
  + // see SIGGRAPH 2014: Advances in Real-Time Rendering
  + // "Next Generation Post-Processing in Call of Duty Advanced Warfare"
  + // Jorge Jimenez
  + const float radius = 1.0;
  + highp vec4 d = vec4(materialParams.resolution.zw, -materialParams.resolution.zw) * radius;
  vec3 c0, c1;
  - c0 = textureLodOffset(materialParams_source, uv, lod, ivec2(-1, -1)).rgb;
  - c0 += textureLodOffset(materialParams_source, uv, lod, ivec2( 1, -1)).rgb;
  - c0 += textureLodOffset(materialParams_source, uv, lod, ivec2( 1, 1)).rgb;
  - c0 += textureLodOffset(materialParams_source, uv, lod, ivec2(-1, 1)).rgb;
  + c0 = textureLod(materialParams_source, uv + d.zw, lod).rgb;
  + c0 += textureLod(materialParams_source, uv + d.xw, lod).rgb;
  + c0 += textureLod(materialParams_source, uv + d.xy, lod).rgb;
  + c0 += textureLod(materialParams_source, uv + d.zy, lod).rgb;
  c0 += 4.0 * textureLod(materialParams_source, uv, lod).rgb;
  - c1 = textureLodOffset(materialParams_source, uv, lod, ivec2(-1, 0)).rgb;
  - c1 += textureLodOffset(materialParams_source, uv, lod, ivec2( 0, -1)).rgb;
  - c1 += textureLodOffset(materialParams_source, uv, lod, ivec2( 1, 0)).rgb;
  - c1 += textureLodOffset(materialParams_source, uv, lod, ivec2( 0, 1)).rgb;
  + c1 = textureLod(materialParams_source, uv + vec2(d.z, 0.0), lod).rgb;
  + c1 += textureLod(materialParams_source, uv + vec2(0.0, d.w), lod).rgb;
  + c1 += textureLod(materialParams_source, uv + vec2(d.x, 0.0), lod).rgb;
  + c1 += textureLod(materialParams_source, uv + vec2( 0.0, d.y), lod).rgb;
  postProcess.color.rgb = (c0 + 2.0 * c1) * (1.0 / 16.0);
  #endif
  }
  