Add example: shapes_math_angle_rotation (angle rotation lines) (#5236)

Co-authored-by: Ray <raysan5@gmail.com>

examples/shapes/shapes_math_angle_rotation.c

@@ -0,0 +1,102 @@
+/*******************************************************************************************
+*
+*   raylib [shapes] example - Math angle rotation lines
+*
+*   Example complexity rating: [★☆☆☆] 1/4
+*
+*   Example originally created with raylib 5.5, last time updated with raylib 5.6
+*
+*   Example contributed by Kris (@krispy-snacc) and reviewed by Ramon Santamaria (@raysan5)
+*
+*   Example licensed under an unmodified zlib/libpng license
+*
+********************************************************************************************/
+
+#include "raylib.h"
+#include "raymath.h" // for DEG2RAD
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 720;
+    const int screenHeight = 400;
+
+    InitWindow(screenWidth, screenHeight, "raylib [shapes] example - angle rotation lines");
+    SetTargetFPS(60);
+
+    Vector2 center = { screenWidth / 2.0f, screenHeight / 2.0f };
+    const float lineLength = 150.0f;
+
+    // Predefined angles for fixed lines
+    int angles[] = { 0, 30, 60, 90 };
+    int numAngles = sizeof(angles)/sizeof(angles[0]);
+
+    float totalAngle = 0.0f; // Animated rotation angle
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        totalAngle += 1.0f; // degrees per frame
+        if (totalAngle >= 360.0f) totalAngle -= 360.0f;
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+            ClearBackground(WHITE);
+
+            DrawText("Fixed angles + rotating line", 10, 10, 20, LIGHTGRAY);
+
+            // Draw fixed-angle lines with colorful gradient
+            for (int i = 0; i < numAngles; i++)
+            {
+                float rad = angles[i] * DEG2RAD;
+                Vector2 end = { center.x + cosf(rad) * lineLength,
+                                center.y + sinf(rad) * lineLength };
+
+                // Gradient color from green → cyan → blue → magenta
+                Color col;
+                switch(i)
+                {
+                    case 0: col = GREEN; break;
+                    case 1: col = ORANGE; break;
+                    case 2: col = BLUE; break;
+                    case 3: col = MAGENTA; break;
+                    default: col = WHITE; break;
+                }
+
+                DrawLineEx(center, end, 5.0f, col);
+
+                // Draw angle label slightly offset along the line
+                Vector2 textPos = { center.x + cosf(rad) * (lineLength + 20),
+                                    center.y + sinf(rad) * (lineLength + 20) };
+                DrawText(TextFormat("%d°", angles[i]), (int)textPos.x, (int)textPos.y, 20, col);
+            }
+
+            // Draw animated rotating line with changing color
+            float animRad = totalAngle * DEG2RAD;
+            Vector2 animEnd = { center.x + cosf(animRad) * lineLength,
+                                center.y + sinf(animRad) * lineLength };
+
+            // Cycle through HSV colors for animated line
+            Color animCol = ColorFromHSV(fmodf(totalAngle, 360.0f), 0.8f, 0.9f);
+            DrawLineEx(center, animEnd, 5.0f, animCol);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}