Merge pull request #36 from jdoleary/shaders

add example "texture_outline"

build.zig

@@ -50,6 +50,11 @@ pub fn build(b: *Builder) void {
             .path = "examples/core/2d_camera.zig",
             .desc = "Shows the functionality of a 2D camera",
         },
+        .{
+            .name = "texture_outline",
+            .path = "examples/shaders/texture_outline.zig",
+            .desc = "Uses a shader to create an outline around a sprite",
+        },
         // .{
         //     .name = "models_loading",
         //     .path = "examples/models/models_loading.zig",

examples/shaders/texture_outline.zig

@@ -0,0 +1,80 @@
+// A raylib port of https://github.com/raysan5/raylib/blob/master/examples/shaders/shaders_texture_outline.c
+
+
+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
+    //--------------------------------------------------------------------------------------
+
+}

resources/shaders/glsl330/outline.fs

@@ -0,0 +1,35 @@
+#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 textureSize;
+uniform float outlineSize;
+uniform vec4 outlineColor;
+
+// Output fragment color
+out vec4 finalColor;
+
+void main()
+{
+    vec4 texel = texture(texture0, fragTexCoord);   // Get texel color
+    vec2 texelScale = vec2(0.0);
+    texelScale.x = outlineSize/textureSize.x;
+    texelScale.y = outlineSize/textureSize.y;
+
+    // We sample four corner texels, but only for the alpha channel (this is for the outline)
+    vec4 corners = vec4(0.0);
+    corners.x = texture(texture0, fragTexCoord + vec2(texelScale.x, texelScale.y)).a;
+    corners.y = texture(texture0, fragTexCoord + vec2(texelScale.x, -texelScale.y)).a;
+    corners.z = texture(texture0, fragTexCoord + vec2(-texelScale.x, texelScale.y)).a;
+    corners.w = texture(texture0, fragTexCoord + vec2(-texelScale.x, -texelScale.y)).a;
+
+    float outline = min(dot(corners, vec4(1.0)), 1.0);
+    vec4 color = mix(vec4(0.0), outlineColor, outline);
+    finalColor = mix(color, texel, texel.a);
+}