Refactor rendering

frontend/src/scripts/drawing/shaders/cave-distance-fs.glsl

@@ -0,0 +1,50 @@
+#version 300 es
+
+precision mediump float;
+
+#define LINE_COUNT {lineCount}
+#define CAVE_COLOR vec3(0.36, 0.38, 0.76)
+#define AIR_COLOR vec3(0.7)
+#define DISTANCE_SCALE {distanceScale}
+#define EDGE_SMOOTHING {edgeSmoothing}
+ 
+uniform float maxMinDistance; 
+
+#if LINE_COUNT > 0
+    uniform struct Line {
+        vec2 from;
+        vec2 toFromDelta;
+        float fromRadius;
+        float toRadius;
+    }[LINE_COUNT] lines;
+#endif
+
+in vec2 worldCoordinates;
+out vec4 fragmentColor;
+
+void main() {
+    #if LINE_COUNT > 0
+        float minDistance = maxMinDistance;
+
+        for (int i = 0; i < LINE_COUNT; i++) {
+            Line line = lines[i];
+            vec2 pa = worldCoordinates - line.from;
+            vec2 ba = line.toFromDelta;
+            float baLength = length(ba);
+            // todo: do we really want this dot(pa / baLength, ba / baLength)
+            float h = clamp(dot(pa / baLength, ba / baLength), 0.0, 1.0);
+            float lineDistance = distance(pa, ba * h) - mix(line.fromRadius, line.toRadius, h);
+
+            minDistance = min(minDistance, lineDistance);
+        }
+
+        float distance = -minDistance;
+        fragmentColor = vec4(
+            mix(CAVE_COLOR, AIR_COLOR, clamp(distance, -EDGE_SMOOTHING, 0.0) / EDGE_SMOOTHING + 1.0),
+            distance / DISTANCE_SCALE
+        );
+    #else
+
+        fragmentColor = vec4(AIR_COLOR, maxMinDistance / DISTANCE_SCALE);
+    #endif
+}