[examples] Added: `shapes_rlgl_color_wheel` example (#5355)

* [examples] Added: `shapes_rlgl_triangle` example

* correct name

* formatting

* Revert "formatting"

This reverts commit f1d246a648.

* Revert "correct name"

This reverts commit 974985ed49.

* Revert "[examples] Added: `shapes_rlgl_triangle` example"

This reverts commit d053b9afa0.

* [examples] Added: `shapes_rlgl_color_wheel` example

* clarify color variable

* formatting

* formatting

* formatting

* formatting

* reduce redundancy

* moved color updating code to update

examples/shapes/shapes_rlgl_color_wheel.c

@@ -0,0 +1,280 @@
+/*******************************************************************************************
+*
+*   raylib [shapes] example - rlgl color wheel
+*
+*   Example complexity rating: [★★★☆] 3/4
+*
+*   Example originally created with raylib 5.6-dev, last time updated with raylib 5.6-dev
+*
+*   Example contributed by Robin (@RobinsAviary) and reviewed by Ramon Santamaria (@raysan5)
+*
+*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+*   BSD-like license that allows static linking with closed source software
+*
+*   Copyright (c) 2025-2025 Robin (@RobinsAviary)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+#include "rlgl.h"
+#include "raymath.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+#define RAYGUI_IMPLEMENTATION
+#include "raygui.h"
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    // The minimum/maximum points the circle can have
+    const unsigned int pointsMin = 3;
+    const unsigned int pointsMax = 256;
+
+    // The current number of points and the radius of the circle
+    unsigned int triangleCount = 64;
+    float pointScale = 150.0f;
+
+    // Slider value, literally maps to value in HSV
+    float value = 1.0f;
+
+    // The center of the screen
+    Vector2 center = { (float)screenWidth/2.0f, (float)screenHeight/2.0f };
+    // The location of the color wheel
+    Vector2 circlePosition = center;
+
+    // The currently selected color
+    Color color = { 255, 255, 255, 255 };
+
+    // Indicates if the slider is being clicked
+    bool sliderClicked = false;
+
+    // Indicates if the current color going to be updated, as well as the handle position
+    bool settingColor = false;
+
+    // How the color wheel will be rendered
+    unsigned int renderType = RL_TRIANGLES;
+
+    // Enable anti-aliasing
+    SetConfigFlags(FLAG_MSAA_4X_HINT);
+    InitWindow(screenWidth, screenHeight, "raylib [shapes] example - rlgl color wheel");
+
+    SetTargetFPS(60);
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        triangleCount += (unsigned int)GetMouseWheelMove();
+        triangleCount = (unsigned int)Clamp((float)triangleCount, (float)pointsMin, (float)pointsMax);
+
+        Rectangle sliderRectangle = { 42.0f, 16.0f + 64.0f + 45.0f, 64.0f, 16.0f };
+        Vector2 mousePosition = GetMousePosition();
+
+        // Checks if the user is hovering over the value slider
+        bool sliderHover = (mousePosition.x >= sliderRectangle.x && mousePosition.y >= sliderRectangle.y && mousePosition.x < sliderRectangle.x + sliderRectangle.width && mousePosition.y < sliderRectangle.y + sliderRectangle.height);
+
+        // Copy color as hex
+        if (IsKeyDown(KEY_LEFT_CONTROL) && IsKeyDown(KEY_C))
+        {
+            if (IsKeyPressed(KEY_C))
+            {
+                SetClipboardText(TextFormat("#%02X%02X%02X", color.r, color.g, color.b));
+            }
+        }
+
+        // Scale up the color wheel, adjusting the handle visually
+        if (IsKeyDown(KEY_UP))
+        {
+            pointScale *= 1.025f;
+
+            if (pointScale > (float)screenHeight/2.0f)
+            {
+                pointScale = (float)screenHeight/2.0f;
+            }
+            else
+            {
+                circlePosition = Vector2Add(Vector2Multiply(Vector2Subtract(circlePosition, center), (Vector2){ 1.025f, 1.025f }), center);
+            }
+        }
+
+        // Scale down the wheel, adjusting the handle visually
+        if (IsKeyDown(KEY_DOWN))
+        {
+            pointScale *= 0.975f;
+
+            if (pointScale < 32.0f)
+            {
+                pointScale = 32.0f;
+            }
+            else
+            {
+                circlePosition = Vector2Add(Vector2Multiply(Vector2Subtract(circlePosition, center), (Vector2){ 0.975f, 0.975f }), center);
+            }
+
+            float distance = Vector2Distance(center, circlePosition)/pointScale;
+            float angle = ((Vector2Angle((Vector2){ 0.0f, -pointScale }, Vector2Subtract(center, circlePosition))/PI + 1.0f) / 2.0f);
+
+            if (distance > 1.0f)
+            {
+                circlePosition = Vector2Add((Vector2){ sinf(angle*(PI * 2.0f)) * pointScale, -cosf(angle*(PI*2.0f))*pointScale }, center);
+            }
+        }
+
+        // Checks if the user clicked on the color wheel
+        if (IsMouseButtonPressed(MOUSE_BUTTON_LEFT) && Vector2Distance(GetMousePosition(), center) <= pointScale + 10.0f)
+        {
+            settingColor = true;
+        }
+
+        // Update flag when mouse button is released
+        if (IsMouseButtonReleased(MOUSE_BUTTON_LEFT)) settingColor = false;
+
+        // Check if the user clicked/released the slider for the color's value
+        if (sliderHover && IsMouseButtonPressed(MOUSE_BUTTON_LEFT)) sliderClicked = true;
+
+        if (sliderClicked && IsMouseButtonReleased(MOUSE_BUTTON_LEFT)) sliderClicked = false;
+
+        // Update render mode accordingly
+        if (IsKeyPressed(KEY_SPACE)) renderType = RL_LINES;
+
+        if (IsKeyReleased(KEY_SPACE)) renderType = RL_TRIANGLES;
+
+        // If the slider or the wheel was clicked, update the current color
+        if (settingColor || sliderClicked)
+        {
+            if (settingColor) {
+                circlePosition = GetMousePosition();
+            }
+
+            float distance = Vector2Distance(center, circlePosition) / pointScale;
+
+            float angle = ((Vector2Angle((Vector2){ 0.0f, -pointScale }, Vector2Subtract(center, circlePosition))/PI + 1.0f)/2.0f);
+            if (settingColor && distance > 1.0f) {
+                circlePosition = Vector2Add((Vector2){ sinf(angle*(PI*2.0f))*pointScale, -cosf(angle*(PI* 2.0f))*pointScale }, center);
+            }
+
+            float angle360 = angle*360.0f;
+
+            float valueActual = Clamp(distance, 0.0f, 1.0f);
+
+            color = ColorLerp((Color){ (int)(value*255.0f), (int)(value*255.0f), (int)(value*255.0f), 255 }, ColorFromHSV(angle360, Clamp(distance, 0.0f, 1.0f), 1.0f), valueActual);
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+        ClearBackground(RAYWHITE);
+
+        // Begin rendering color wheel
+        rlBegin(renderType);
+        for (unsigned int i = 0; i < triangleCount; i++)
+        {
+            float angleOffset = ((PI*2.0f)/(float)triangleCount);
+            float angle = angleOffset*(float)i;
+            float angleOffsetCalculated = ((float)i + 1)*angleOffset;
+            Vector2 scale = (Vector2){ pointScale, pointScale };
+
+            Vector2 offset = Vector2Multiply((Vector2){ sinf(angle), -cosf(angle) }, scale);
+            Vector2 offset2 = Vector2Multiply((Vector2){ sinf(angleOffsetCalculated), -cosf(angleOffsetCalculated) }, scale);
+
+            Vector2 position = Vector2Add(center, offset);
+            Vector2 position2 = Vector2Add(center, offset2);
+
+            float angleNonRadian = (angle/(2.0f*PI))*360.0f;
+            float angleNonRadianOffset = (angleOffset/(2.0f*PI))*360.0f;
+
+            Color currentColor = ColorFromHSV(angleNonRadian, 1.0f, 1.0f);
+            Color offsetColor = ColorFromHSV(angleNonRadian + angleNonRadianOffset, 1.0f, 1.0f);
+
+            // Input vertices differently depending on mode
+            if (renderType == RL_TRIANGLES)
+            {
+                // RL_TRIANGLES expects three vertices per triangle
+                rlColor4ub(currentColor.r, currentColor.g, currentColor.b, currentColor.a);
+                rlVertex2f(position.x, position.y);
+                rlColor4f(value, value, value, 1.0f);
+                rlVertex2f(center.x, center.y);
+                rlColor4ub(offsetColor.r, offsetColor.g, offsetColor.b, offsetColor.a);
+                rlVertex2f(position2.x, position2.y);
+            }
+            else if (renderType == RL_LINES)
+            {
+                // RL_LINES expects two vertices per line
+                rlColor4ub(currentColor.r, currentColor.g, currentColor.b, currentColor.a);
+                rlVertex2f(position.x, position.y);
+                rlColor4ub(WHITE.r, WHITE.g, WHITE.b, WHITE.a);
+                rlVertex2f(center.x, center.y);
+
+                rlVertex2f(center.x, center.y);
+                rlColor4ub(offsetColor.r, offsetColor.g, offsetColor.b, offsetColor.a);
+                rlVertex2f(position2.x, position2.y);
+
+                rlVertex2f(position2.x, position2.y);
+                rlColor4ub(currentColor.r, currentColor.g, currentColor.b, currentColor.a);
+                rlVertex2f(position.x, position.y);
+            }
+        }
+        rlEnd();
+
+        // Make the handle slightly more visible overtop darker colors
+        Color handleColor = BLACK;
+
+        if (Vector2Distance(center, circlePosition)/pointScale <= 0.5f && value <= 0.5f)
+        {
+            handleColor = DARKGRAY;
+        }
+
+        // Draw the color handle
+        DrawCircleLinesV(circlePosition, 4.0f, handleColor);
+
+        // Draw the color in a preview, with a darkened outline.
+        DrawRectangleV((Vector2){ 8.0f, 8.0f }, (Vector2){ 64.0f, 64.0f }, color);
+        DrawRectangleLinesEx((Rectangle){ 8.0f, 8.0f, 64.0f, 64.0f }, 2.0f, ColorLerp(color, BLACK, 0.5f));
+
+        // Draw current color as hex and decimal
+        DrawText(TextFormat("#%02X%02X%02X\n(%d, %d, %d)", color.r, color.g, color.b, color.r, color.g, color.b), 8, 8 + 64 + 8, 20, DARKGRAY);
+
+        // Update the visuals for the copying text
+        Color copyColor = DARKGRAY;
+        unsigned int offset = 0;
+        if (IsKeyDown(KEY_LEFT_CONTROL) && IsKeyDown(KEY_C))
+        {
+            copyColor = DARKGREEN;
+            offset = 4;
+        }
+
+        // Draw the copying text
+        DrawText("press ctrl+c to copy!", 8, 425 - offset, 20, copyColor);
+
+        // Display the number of rendered triangles
+        DrawText(TextFormat("triangle count: %d", triangleCount), 8, 395, 20, DARKGRAY);
+
+        // Slider to change color's value
+        GuiSliderBar(sliderRectangle, "value: ", "", &value, 0.0f, 1.0f);
+
+        // Draw FPS next to outlined color preview
+        DrawFPS(64 + 16, 8);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}