Add DrawSplineSegmentLinearVar

examples/shapes/shapes_splines_drawing.c

@@ -35,6 +35,7 @@ typedef enum {
     SPLINE_BASIS,           // B-Spline
     SPLINE_CATMULLROM,      // Catmull-Rom
     SPLINE_BEZIER,          // Cubic Bezier
+    SPLINE_LINEAR_VAR,      // Linear, variable thickness
     SPLINE_BEZIER_VAR       // Cubic Bezier, variable thickness
 } SplineType;
 
@@ -79,7 +80,8 @@ int main(void)
 
     // Spline config variables
     float splineThickness = 8.0f;
-    int splineTypeActive = SPLINE_BEZIER_VAR; // 0-Linear, 1-BSpline, 2-CatmullRom, 3-Bezier, 4-BezierVar
+    int splineTypeActive = SPLINE_LINEAR_VAR; // 0-Linear, 1-BSpline, 2-CatmullRom, 3-Bezier, 4-LinearVar, 5-BezierVar
+                                              // TODO: Change the default back to SPLINE_LINEAR when finished testing
     bool splineTypeEditMode = false; 
     bool splineHelpersActive = true;
     
@@ -155,6 +157,7 @@ int main(void)
         else if (IsKeyPressed(KEY_THREE)) splineTypeActive = 2;
         else if (IsKeyPressed(KEY_FOUR)) splineTypeActive = 3;
         else if (IsKeyPressed(KEY_FIVE)) splineTypeActive = 4;
+        else if (IsKeyPressed(KEY_SIX)) splineTypeActive = 5;
         //----------------------------------------------------------------------------------
 
         // Draw
@@ -218,6 +221,21 @@ int main(void)
                 }
                 */
             }
+            else if (splineTypeActive == SPLINE_LINEAR_VAR)
+            {
+                float thicks[] = {
+                    0.0f,
+                    splineThickness,
+                    splineThickness,
+                    0.0f,
+                };
+
+                // Draw spline: variable-width linear
+                for (int i = 0; i < pointCount - 1; ++i)
+                {
+                    DrawSplineSegmentLinearVar(points[i], points[i+1], thicks, 4, RED);
+                }
+            }
             else if (splineTypeActive == SPLINE_BEZIER_VAR)
             {
                 float thicks[] = {
@@ -238,7 +256,7 @@ int main(void)
                 
                 pointsInterleaved[3*(pointCount - 1)] = points[pointCount - 1];
 
-                // Draw spline: cubic-bezier (with control points)
+                // Draw spline: variable-width cubic-bezier (with control points)
                 for (int i = 0; i < pointCount - 1; ++i)
                 {
                     DrawSplineSegmentBezierCubicVar(points[i], control[i].start, control[i].end, points[i+1], thicks, 4, RED);
@@ -272,6 +290,7 @@ int main(void)
                 {
                     DrawCircleLinesV(points[i], (focusedPoint == i)? 12.0f : 8.0f, (focusedPoint == i)? BLUE: DARKBLUE);
                     if ((splineTypeActive != SPLINE_LINEAR) &&
+                        (splineTypeActive != SPLINE_LINEAR_VAR) &&
                         (splineTypeActive != SPLINE_BEZIER) &&
                         (splineTypeActive != SPLINE_BEZIER_VAR) &&
                         (i < pointCount - 1)) DrawLineV(points[i], points[i + 1], GRAY);
@@ -292,7 +311,7 @@ int main(void)
             GuiUnlock();
 
             GuiLabel((Rectangle){ 12, 10, 140, 24 }, "Spline type:");
-            if (GuiDropdownBox((Rectangle){ 12, 8 + 24, 140, 28 }, "LINEAR;BSPLINE;CATMULLROM;BEZIER;BEZIER VARIABLE", &splineTypeActive, splineTypeEditMode)) splineTypeEditMode = !splineTypeEditMode;
+            if (GuiDropdownBox((Rectangle){ 12, 8 + 24, 140, 28 }, "LINEAR;BSPLINE;CATMULLROM;BEZIER;LINEAR VARIABLE;BEZIER VARIABLE", &splineTypeActive, splineTypeEditMode)) splineTypeEditMode = !splineTypeEditMode;
 
         EndDrawing();
         //----------------------------------------------------------------------------------

src/raylib.h

@@ -1298,6 +1298,7 @@ RLAPI void DrawSplineSegmentBasis(Vector2 p1, Vector2 p2, Vector2 p3, Vector2 p4
 RLAPI void DrawSplineSegmentCatmullRom(Vector2 p1, Vector2 p2, Vector2 p3, Vector2 p4, float thick, Color color); // Draw spline segment: Catmull-Rom, 4 points
 RLAPI void DrawSplineSegmentBezierQuadratic(Vector2 p1, Vector2 c2, Vector2 p3, float thick, Color color); // Draw spline segment: Quadratic Bezier, 2 points, 1 control point
 RLAPI void DrawSplineSegmentBezierCubic(Vector2 p1, Vector2 c2, Vector2 c3, Vector2 p4, float thick, Color color); // Draw spline segment: Cubic Bezier, 2 points, 2 control points
+RLAPI void DrawSplineSegmentLinearVar(Vector2 p1, Vector2 p2, const float* thicks, int thickCount, Color color); // Draw spline segment with variable thickness: Linear Bezier, 2 points
 RLAPI void DrawSplineSegmentBezierCubicVar(Vector2 p1, Vector2 c2, Vector2 c3, Vector2 p4, const float* thicks, int thickCount, Color color); // Draw spline segment with variable thickness: Cubic Bezier, 2 points, 2 control points
 
 // Spline segment point evaluation functions, for a given t [0.0f .. 1.0f]

src/rshapes.c

@@ -2107,6 +2107,89 @@ void DrawSplineSegmentBezierCubic(Vector2 p1, Vector2 c2, Vector2 c3, Vector2 p4
     DrawTriangleStrip(points, 2*SPLINE_SEGMENT_DIVISIONS + 2, color);
 }
 
+// Draw spline segment with variable thickness: Linear, 2 points
+void DrawSplineSegmentLinearVar(Vector2 p1, Vector2 p2, const float* thicks, int thickCount, Color color)
+{
+    if (thickCount >= 4)
+    {
+        const float step = 1.0f/SPLINE_SEGMENT_DIVISIONS;
+
+        Vector2 previous[2] = { 0 };
+        Vector2 current[2] = { 0 };
+        float t = 0.0f;
+
+        // Linear velocity does not change across the curve
+        Vector2 tangent = { 0 };
+
+        tangent.x = p2.x - p1.x;
+        tangent.y = p2.y - p1.y;
+
+        float speedSqr = tangent.x*tangent.x + tangent.y*tangent.y;
+
+        if (speedSqr > 0)
+        {
+            float speedInv = 1.0f/sqrtf(speedSqr);
+            tangent.x *= speedInv;
+            tangent.y *= speedInv;
+
+            rlBegin(RL_TRIANGLES);
+                rlColor4ub(color.r, color.g, color.b, color.a);
+
+                for (int i = 0; i <= SPLINE_SEGMENT_DIVISIONS; i++)
+                {
+                    t = step*(float)i;
+
+                    Vector2 point = { 0 };
+
+                    point.x = p1.x*(1.0f - t) + p2.x*t;
+                    point.y = p1.y*(1.0f - t) + p2.y*t;
+
+                    // TODO: Doesn't seem to be working properly for more than 3 distinct values
+                    float thick;
+                    {
+                        float tMajor = t*(float)thickCount;
+                        int tIndex = (int)tMajor;
+                        float tMinor = tMajor - (float)tIndex;
+                        tIndex *= 3;
+                        if (tIndex >= thickCount - 3)
+                        {
+                            tIndex = thickCount - 4;
+                            tMinor = 1.0f;
+                        }
+                        float a = powf(1.0f - t, 3);
+                        float b = 3.0f*powf(1.0f - t, 2)*t;
+                        float c = 3.0f*(1.0f - t)*t*t;
+                        float d = t*t*t;
+
+                        thick = a*thicks[tIndex] + b*thicks[tIndex + 1] + c*thicks[tIndex + 2] + d*thicks[tIndex + 3];
+                    }
+
+                    current[0].x = point.x + thick*tangent.y;
+                    current[0].y = point.y - thick*tangent.x;
+
+                    current[1].x = point.x - thick*tangent.y;
+                    current[1].y = point.y + thick*tangent.x;
+
+                    if (i > 0)
+                    {
+                        rlVertex2f(current[0].x, current[0].y);
+                        rlVertex2f(previous[0].x, previous[0].y);
+                        rlVertex2f(previous[1].x, previous[1].y);
+
+                        rlVertex2f(current[1].x, current[1].y);
+                        rlVertex2f(current[0].x, current[0].y);
+                        rlVertex2f(previous[1].x, previous[1].y);
+                    }
+
+                    previous[0] = current[0];
+                    previous[1] = current[1];
+                }
+
+            rlEnd();
+        }
+    }
+}
+
 // Draw spline segment with variable thickness: Cubic Bezier, 2 points, 2 control points
 void DrawSplineSegmentBezierCubicVar(Vector2 p1, Vector2 c2, Vector2 c3, Vector2 p4, const float* thicks, int thickCount, Color color)
 {
@@ -2138,8 +2221,8 @@ void DrawSplineSegmentBezierCubicVar(Vector2 p1, Vector2 c2, Vector2 c3, Vector2
                 float speedSqr = (tangent.x*tangent.x + tangent.y*tangent.y);
                 if (speedSqr == 0) continue;
                 float speedInv = 1.0f/sqrtf(speedSqr);
-                tangent.x = tangent.x*speedInv;
+                tangent.x *= speedInv;
-                tangent.y = tangent.y*speedInv;
+                tangent.y *= speedInv;
 
                 Vector2 point = { 0 };
                 {
@@ -2178,7 +2261,7 @@ void DrawSplineSegmentBezierCubicVar(Vector2 p1, Vector2 c2, Vector2 c3, Vector2
                 current[1].x = point.x - thick*tangent.y;
                 current[1].y = point.y + thick*tangent.x;
 
-                if (i > 0)
+                if (i > 0) // TODO: `previous` may be unassigned in i=1 if i=0 had a `speedSqr` of 0
                 {
                     rlVertex2f(current[0].x, current[0].y);
                     rlVertex2f(previous[0].x, previous[0].y);