From f3adde8bbd7fbc930f5b3abd57a5481413ff5644 Mon Sep 17 00:00:00 2001
From: Ray <raysan5@gmail.com>
Date: Fri, 15 Dec 2023 18:40:19 +0100
Subject: [PATCH] REVIEWED: `DrawSplineLinear()` to `SUPPORT_SPLINE_MITERS`

---
 src/rshapes.c | 53 ++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 40 insertions(+), 13 deletions(-)

diff --git a/src/rshapes.c b/src/rshapes.c
index b7fc0ed7..b8c17e70 100644
--- a/src/rshapes.c
+++ b/src/rshapes.c
@@ -1546,13 +1546,12 @@ void DrawPolyLinesEx(Vector2 center, int sides, float radius, float rotation, fl
 // Draw spline: linear, minimum 2 points
 void DrawSplineLinear(Vector2 *points, int pointCount, float thick, Color color)
 {
-    if (pointCount < 2)
-    {
-        return;
-    }
-    
+    if (pointCount < 2) return;
+
+#if defined(SUPPORT_SPLINE_MITERS)
     Vector2 prevNormal = (Vector2){-(points[1].y - points[0].y), (points[1].x - points[0].x)};
     float prevLength = sqrtf(prevNormal.x*prevNormal.x + prevNormal.y*prevNormal.y);
+    
     if (prevLength > 0.0f)
     {
         prevNormal.x /= prevLength;
@@ -1564,16 +1563,17 @@ void DrawSplineLinear(Vector2 *points, int pointCount, float thick, Color color)
         prevNormal.y = 0.0f;
     }
 
-    Vector2 prevRadius = {.5f * thick * prevNormal.x, .5f * thick * prevNormal.y};
+    Vector2 prevRadius = { 0.5f*thick*prevNormal.x, 0.5f*thick*prevNormal.y };
     
     for (int i = 0; i < pointCount - 1; i++)
     {
-        Vector2 normal = {0};
+        Vector2 normal = { 0 };
 
         if (i < pointCount - 2)
         {
-            normal = (Vector2){-(points[i+2].y - points[i+1].y), (points[i+2].x - points[i+1].x)};
+            normal = (Vector2){-(points[i + 2].y - points[i + 1].y), (points[i + 2].x - points[i + 1].x)};
             float normalLength = sqrtf(normal.x*normal.x + normal.y*normal.y);
+            
             if (normalLength > 0.0f)
             {
                 normal.x /= normalLength;
@@ -1590,8 +1590,9 @@ void DrawSplineLinear(Vector2 *points, int pointCount, float thick, Color color)
             normal = prevNormal;
         }
 
-        Vector2 radius = {prevNormal.x + normal.x, prevNormal.y + normal.y};
+        Vector2 radius = { prevNormal.x + normal.x, prevNormal.y + normal.y };
         float radiusLength = sqrtf(radius.x*radius.x + radius.y*radius.y);
+        
         if (radiusLength > 0.0f)
         {
             radius.x /= radiusLength;
@@ -1603,12 +1604,12 @@ void DrawSplineLinear(Vector2 *points, int pointCount, float thick, Color color)
             radius.y = 0.0f;
         }
 
-        float cosTheta = radius.x * normal.x + radius.y * normal.y;
+        float cosTheta = radius.x*normal.x + radius.y*normal.y;
 
         if (cosTheta != 0.0f)
         {
-            radius.x *= thick * .5f / cosTheta;
-            radius.y *= thick * .5f / cosTheta;
+            radius.x *= (thick*0.5f/cosTheta);
+            radius.y *= (thick*0.5f/cosTheta);
         }
         else
         {
@@ -1628,8 +1629,34 @@ void DrawSplineLinear(Vector2 *points, int pointCount, float thick, Color color)
         prevRadius = radius;
         prevNormal = normal;
     }
-#if defined(SUPPORT_SPLINE_SEGMENT_CAPS)
 
+#else   // !SUPPORT_SPLINE_MITTERS
+
+    Vector2 delta = { 0 };
+    float length = 0.0f;
+    float scale = 0.0f;
+
+    for (int i = 0; i < pointCount - 1; i++)
+    {
+        delta = (Vector2){ points[i + 1].x - points[i].x, points[i + 1].y - points[i].y };
+        length = sqrtf(delta.x*delta.x + delta.y*delta.y);
+
+        if (length > 0) scale = thick/(2*length);
+
+        Vector2 radius = { -scale*delta.y, scale*delta.x };
+        Vector2 strip[4] = {
+            { points[i].x - radius.x, points[i].y - radius.y },
+            { points[i].x + radius.x, points[i].y + radius.y },
+            { points[i + 1].x - radius.x, points[i + 1].y - radius.y },
+            { points[i + 1].x + radius.x, points[i + 1].y + radius.y }
+        };
+
+        DrawTriangleStrip(strip, 4, color);
+    }
+#endif
+    
+#if defined(SUPPORT_SPLINE_SEGMENT_CAPS)
+    // TODO: Add spline segment rounded caps at the begin/end of the spline
 #endif
 }