Fix line angle calculation.

In calculating angles related to lines, two angles were averaged using (a + b) / 2, which doesn't work in the general case.
OpenGeoscience · Jul 18, 2016 · 6d53729 · 6d53729
1 parent 8d68527
commit 6d53729
Showing 1 changed file with 6 additions and 7 deletions.
diff --git a/src/gl/lineFeature.js b/src/gl/lineFeature.js
@@ -61,8 +61,7 @@ var gl_lineFeature = function (arg) {
  'uniform float pixelWidth;',
  'uniform float aspect;',
 
- 'varying vec3 strokeColorVar;',
- 'varying float strokeOpacityVar;',
+ 'varying vec4 strokeColorVar;',
 
  'void main(void)',
  '{',
@@ -85,8 +84,7 @@ var gl_lineFeature = function (arg) {
  ' if (worldPrev.w != 0.0) {',
  ' worldPrev = worldPrev/worldPrev.w;',
  ' }',
- ' strokeColorVar = strokeColor;',
- ' strokeOpacityVar = strokeOpacity;',
+ ' strokeColorVar = vec4(strokeColor, strokeOpacity);',
  ' vec2 deltaNext = worldNext.xy - worldPos.xy;',
  ' vec2 deltaPrev = worldPos.xy - worldPrev.xy;',
  ' float angleNext = 0.0, anglePrev = 0.0;',
@@ -96,6 +94,8 @@ var gl_lineFeature = function (arg) {
  ' else anglePrev = atan(deltaPrev.y / aspect, deltaPrev.x);',
  ' if (deltaNext.xy == vec2(0.0, 0.0)) angleNext = anglePrev;',
  ' float angle = (anglePrev + angleNext) / 2.0;',
+ ' if (abs(anglePrev - angleNext) >= PI)',
+ ' angle += PI;',
  ' float cosAngle = cos(anglePrev - angle);',
  ' if (cosAngle < 0.1) { cosAngle = sign(cosAngle) * 1.0; angle = 0.0; }',
  ' float distance = (offset * strokeWidth * pixelWidth) /',
@@ -115,10 +115,9 @@ var gl_lineFeature = function (arg) {
  '#ifdef GL_ES',
  ' precision highp float;',
  '#endif',
- 'varying vec3 strokeColorVar;',
- 'varying float strokeOpacityVar;',
+ 'varying vec4 strokeColorVar;',
  'void main () {',
- ' gl_FragColor = vec4 (strokeColorVar, strokeOpacityVar);',
+ ' gl_FragColor = strokeColorVar;',
  '}'
  ].join('\n'),
  shader = new vgl.shader(vgl.GL.FRAGMENT_SHADER);