Add example shaders_shapes_outline.c (#1883)

examples/shaders/resources/LICENSE.md

@@ -9,3 +9,5 @@
 | raysan.png         | [@raysan5](https://github.com/raysan5)      | [CC0](https://creativecommons.org/publicdomain/zero/1.0/)   | - |
 | space.png          | ❔             | ❔       | - |
 | texel_checker.png  | [@raysan5](https://github.com/raysan5)      | [CC0](https://creativecommons.org/publicdomain/zero/1.0/)   | Made with [UV Checker Map Maker](http://uvchecker.byvalle.com/) |
+| egg.png            | [@GoldenThumbs](https://github.com/GoldenThumbs) |
+| torus.png          | [@GoldenThumbs](https://github.com/GoldenThumbs) |

examples/shaders/resources/shaders/glsl100/outline.fs

@@ -0,0 +1,35 @@
+#version 100
+
+precision mediump float;
+
+// Input vertex attributes (from vertex shader)
+varying vec2 fragTexCoord;
+varying vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform vec4 colDiffuse;
+uniform vec2 texScale;
+
+// Function for drawing outlines on alpha-blended textures
+vec4 DrawOutline(sampler2D tex, vec2 uv, vec2 lineScale, vec3 lineCol)
+{
+	vec2 texelScale = 1.0 / lineScale;
+	vec4 center = texture2D(tex, uv); // We sample the center texel, (with all color data)
+	// Next we sample four corner texels, but only for the alpha channel (this is for the outline)
+	vec4 corners;
+	corners.x = texture2D(tex, uv+vec2( texelScale.x, texelScale.y)).a;
+	corners.y = texture2D(tex, uv+vec2( texelScale.x,-texelScale.y)).a;
+	corners.z = texture2D(tex, uv+vec2(-texelScale.x, texelScale.y)).a;
+	corners.w = texture2D(tex, uv+vec2(-texelScale.x,-texelScale.y)).a;
+	
+	float outline = min(dot(corners, vec4(1.0)), 1.0);
+	vec4 col = mix(vec4(0.0), vec4(lineCol, 1.0), outline);
+	col = mix(col, center, center.a);
+	return col;
+}
+
+void main()
+{
+	gl_FragColor = DrawOutline(texture0, fragTexCoord, texScale, vec3(0.0));
+}

examples/shaders/resources/shaders/glsl330/outline.fs

@@ -0,0 +1,36 @@
+#version 330
+
+// Input vertex attributes (from vertex shader)
+in vec2 fragTexCoord;
+in vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform vec4 colDiffuse;
+uniform vec2 texScale;
+
+// Output fragment color
+out vec4 finalColor;
+
+// Function for drawing outlines on alpha-blended textures
+vec4 DrawOutline(sampler2D tex, vec2 uv, vec2 lineScale, vec3 lineCol)
+{
+	vec2 texelScale = 1.0 / lineScale;
+	vec4 center = texture(tex, uv); // We sample the center texel, (with all color data)
+	// Next we sample four corner texels, but only for the alpha channel (this is for the outline)
+	vec4 corners;
+	corners.x = texture(tex, uv+vec2( texelScale.x, texelScale.y)).a;
+	corners.y = texture(tex, uv+vec2( texelScale.x,-texelScale.y)).a;
+	corners.z = texture(tex, uv+vec2(-texelScale.x, texelScale.y)).a;
+	corners.w = texture(tex, uv+vec2(-texelScale.x,-texelScale.y)).a;
+	
+	float outline = min(dot(corners, vec4(1.0)), 1.0);
+	vec4 col = mix(vec4(0.0), vec4(lineCol, 1.0), outline);
+	col = mix(col, center, center.a);
+	return col;
+}
+
+void main()
+{
+	finalColor = DrawOutline(texture0, fragTexCoord, texScale, vec3(0.0));
+}

examples/shaders/shaders_shapes_outline.c

@@ -0,0 +1,84 @@
+/*******************************************************************************************
+*
+*   raylib [shaders] example - Apply an outline to a texture
+*	
+*   NOTE: This example requires raylib OpenGL 3.3 or ES2 versions for shaders support,
+*         OpenGL 1.1 does not support shaders, recompile raylib to OpenGL 3.3 version.
+*
+*   NOTE: Shaders used in this example are #version 330 (OpenGL 3.3).
+*
+*   This example has been created using raylib 3.8 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+* 
+*   Example contributed by Samuel Skiff (@GoldenThumbs)
+*
+*   Copyright (c) 2021 Samuel SKiff (@GoldenThumbs) and Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#if defined(PLATFORM_DESKTOP)
+    #define GLSL_VERSION            330
+#else   // PLATFORM_RPI, PLATFORM_ANDROID, PLATFORM_WEB
+    #define GLSL_VERSION            100
+#endif
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [shaders] example - Apply an outline to a texture");
+
+	Texture2D egg = LoadTexture("resources/egg.png");
+	Texture2D torus = LoadTexture("resources/torus.png");
+	Shader outline = LoadShader(0, TextFormat("resources/shaders/glsl%i/outline.fs", GLSL_VERSION));
+
+	float oScale = 16.0;
+	float tScale[2] = { 16.0f*4, 16.0f*4 };
+	SetShaderValue(outline, GetShaderLocation(outline, "texScale"), tScale, SHADER_UNIFORM_VEC2);
+
+    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
+        //----------------------------------------------------------------------------------
+        // TODO: Update your variables here
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            BeginShaderMode(outline);
+                DrawTextureEx(egg, (Vector2){ 0, 230 }, 0.0, oScale, WHITE);
+                DrawTextureEx(torus, (Vector2){ 544, 230 }, 0.0, oScale, WHITE);
+            EndShaderMode();
+
+			DrawText("Shader-based outlines for textures", 190, 200, 20, LIGHTGRAY);
+
+            DrawFPS(710, 10);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+	UnloadTexture(egg);
+	UnloadTexture(torus);
+	UnloadShader(outline);
+
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}