Post Game jam commit

shaders/post_processing.gdshader

@@ -0,0 +1,30 @@
+shader_type canvas_item;
+
+uniform sampler2D screen_texture : hint_screen_texture, repeat_disable, filter_nearest;
+
+uniform float brightness : hint_range(0.0, 2.0) = 1.0;
+uniform float contrast : hint_range(0.0, 2.0) = 1.0;
+uniform float saturation : hint_range(0.0, 2.0) = 1.0;
+
+void fragment() {
+    // 1. Get the screen color
+    vec4 tex_color = textureLod(screen_texture, SCREEN_UV, 0.0);
+    vec3 color = tex_color.rgb;
+
+    // 2. Adjust Brightness
+    // Simply multiply by the brightness factor
+    color *= brightness;
+
+    // 3. Adjust Contrast
+    // Interpolate between a neutral gray (0.5) and the current color
+    color = mix(vec3(0.5), color, contrast);
+
+    // 4. Adjust Saturation
+    // Calculate grayscale (luminance) using standard weights
+    float luminance = dot(color, vec3(0.2126, 0.7152, 0.0722));
+    vec3 grayscale = vec3(luminance);
+    // Interpolate between grayscale and color
+    color = mix(grayscale, color, saturation);
+
+    COLOR = vec4(color, tex_color.a);
+}