add example "texture_outline"

Which demonstrates shader support

examples/shaders/texture_outline.zig

@@ -0,0 +1,77 @@
+const rl = @import("raylib");
+const std = @import("std");
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+pub fn main() anyerror!void {
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const screenWidth = 800;
+    const screenHeight = 450;
+
+    rl.InitWindow(screenWidth, screenHeight, "raylib [shaders] example - Apply an outline to a texture");
+
+    const texture: rl.Texture2D = rl.LoadTexture("resources/textures/fudesumi.png");
+    
+    const shdrOutline: rl.Shader = rl.LoadShader(0, rl.TextFormat("resources/shaders/glsl330/outline.fs", @intCast(c_int, 330)));
+
+    var outlineSize: f32 = 2.0;
+    const outlineColor = [4]f32{ 1.0, 0.0, 0.0, 1.0 };     // Normalized RED color 
+    const textureSize = rl.Vector2{ .x=@intToFloat(f32, texture.width), .y=@intToFloat(f32,texture.height) };
+    
+    // Get shader locations
+    const outlineSizeLoc = rl.GetShaderLocation(shdrOutline, "outlineSize");
+    const outlineColorLoc = rl.GetShaderLocation(shdrOutline, "outlineColor");
+    const textureSizeLoc = rl.GetShaderLocation(shdrOutline, "textureSize");
+    
+    // Set shader values (they can be changed later)
+    rl.SetShaderValue(shdrOutline, outlineSizeLoc, &outlineSize, @enumToInt(rl.ShaderUniformDataType.SHADER_UNIFORM_FLOAT));
+    rl.SetShaderValue(shdrOutline, outlineColorLoc, &outlineColor, @enumToInt(rl.ShaderUniformDataType.SHADER_UNIFORM_VEC4));
+    rl.SetShaderValue(shdrOutline, textureSizeLoc, &textureSize, @enumToInt(rl.ShaderUniformDataType.SHADER_UNIFORM_VEC2));
+
+    rl.SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!rl.WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        outlineSize += rl.GetMouseWheelMove();
+        if (outlineSize < 1.0) outlineSize = 1.0;
+        
+        rl.SetShaderValue(shdrOutline, outlineSizeLoc, &outlineSize, @enumToInt(rl.ShaderUniformDataType.SHADER_UNIFORM_FLOAT));
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        rl.BeginDrawing();
+
+            rl.ClearBackground(rl.RAYWHITE);
+
+            rl.BeginShaderMode(shdrOutline);
+            
+                rl.DrawTexture(texture, @divFloor(rl.GetScreenWidth(),2) - @divFloor(texture.width,2), -30, rl.WHITE);
+                
+            rl.EndShaderMode();
+
+            rl.DrawText("Shader-based\ntexture\noutline", 10, 10, 20, rl.GRAY);
+            
+            rl.DrawText(rl.TextFormat("Outline size: %i px", @floatToInt(i32, outlineSize)), 10, 120, 20, rl.MAROON);
+
+            rl.DrawFPS(710, 10);
+
+        rl.EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    rl.UnloadTexture(texture);
+    rl.UnloadShader(shdrOutline);
+
+    rl.CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+}