Added scissor test and mouse painting examples proposed in #890 (#919)

- Updated Makefile with new examples

examples/textures/textures_mouse_painting.c

@@ -0,0 +1,136 @@
+/*******************************************************************************************
+*
+*   raylib [textures] example - Mouse painting
+*
+*   This example has been created using raylib 2.5 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2019 Chris Dill (@MysteriousSpace)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#define MAX_COLORS_COUNT 21 // Number of colors available
+
+int main(void) 
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight,
+                "raylib [textures] example - texture painting");
+
+    // Different colours to choose from
+    Color colors[MAX_COLORS_COUNT] = {
+        DARKGRAY,  MAROON, ORANGE, DARKGREEN, DARKBLUE, DARKPURPLE, DARKBROWN,
+        GRAY,      RED,    GOLD,   LIME,      BLUE,     VIOLET,     BROWN,
+        LIGHTGRAY, PINK,   YELLOW, GREEN,     SKYBLUE,  PURPLE,     BEIGE};
+
+    const char *colorNames[MAX_COLORS_COUNT] = {
+        "DARKGRAY",  "MAROON", "ORANGE",    "DARKGREEN", "DARKBLUE", "DARKPURPLE",
+        "DARKBROWN", "GRAY",   "RED",       "GOLD",      "LIME",     "BLUE",
+        "VIOLET",    "BROWN",  "LIGHTGRAY", "PINK",      "YELLOW",   "GREEN",
+        "SKYBLUE",   "PURPLE", "BEIGE"};
+
+    int colorState = 0;
+    int brushSize = 20;
+
+    // Create a RenderTexture2D to use as a canvas
+    RenderTexture2D target = LoadRenderTexture(screenWidth, screenHeight);
+    Color clearColor = RAYWHITE;
+
+    BeginTextureMode(target);
+    ClearBackground(clearColor);
+    EndTextureMode();
+
+    SetTargetFPS(60); // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose()) // Detect window close button or ESC key
+    {
+	    // Update
+	    //----------------------------------------------------------------------------------
+	    // Switch between colors
+	    if (IsKeyPressed(KEY_RIGHT))
+	        colorState++;
+	    else if (IsKeyPressed(KEY_LEFT))
+	        colorState--;
+
+	    if (colorState >= MAX_COLORS_COUNT)
+	        colorState = 0;
+	    else if (colorState < 0)
+	        colorState = MAX_COLORS_COUNT - 1;
+
+	    brushSize += GetMouseWheelMove() * 5;
+	    if (brushSize < 0)
+	        brushSize = 0;
+	    if (brushSize > 50)
+	        brushSize = 50;
+
+	    Vector2 position = GetMousePosition();
+
+	    if (IsKeyPressed(KEY_C)) {
+	        BeginTextureMode(target);
+	        ClearBackground(RAYWHITE);
+	        EndTextureMode();
+	    }
+
+	    if (IsMouseButtonDown(MOUSE_LEFT_BUTTON)) {
+	        TraceLog(LOG_INFO, "Painting x: %f y: %f", position.x, position.y);
+	        BeginTextureMode(target);
+	        DrawCircle(position.x, position.y, brushSize, colors[colorState]);
+	        EndTextureMode();
+	    }
+
+	    if (IsMouseButtonDown(MOUSE_RIGHT_BUTTON)) {
+	        TraceLog(LOG_INFO, "Erasing x: %f y: %f", position.x, position.y);
+	        BeginTextureMode(target);
+	        DrawCircle(position.x, position.y, brushSize, clearColor);
+	        EndTextureMode();
+	    }
+
+	    if (IsKeyPressed(KEY_S)) {
+	        TakeScreenshot("textures_mouse_painting.png");
+	    }
+	    //----------------------------------------------------------------------------------
+
+	    // Draw
+	    //----------------------------------------------------------------------------------
+	    BeginDrawing();
+
+	    ClearBackground(RAYWHITE);
+
+	        // NOTE: Render texture must be y-flipped due to default OpenGL coordinates
+	        // (left-bottom)
+	        DrawTextureRec(target.texture, (Rectangle){0, 0, target.texture.width, -target.texture.height}, (Vector2){0, 0}, WHITE);
+
+	        // Draw 2d shapes and text over drawn texture
+	        DrawRectangle(0, 9, 380, 60, Fade(LIGHTGRAY, 0.7f));
+
+	        DrawText("COLOR:", 10, 15, 20, BLACK);
+	        DrawText(colorNames[colorState], 130, 15, 20, RED);
+	        DrawText("< >", 340, 10, 30, DARKBLUE);
+
+	        DrawText("Size:", 10, 40, 20, BLACK);
+	        DrawText(FormatText("%i", brushSize), 130, 40, 20, RED);
+
+	        DrawCircle(GetMouseX(), GetMouseY(), brushSize, colors[colorState]);
+
+	        DrawFPS(700, 15);
+
+	    EndDrawing();
+	    //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadRenderTexture(target);
+    CloseWindow(); // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}