Add Pixelated/sharp bilinear filter, closes #746

Cocoa/GBApp.m

@@ -80,7 +80,7 @@ static uint32_t color_to_int(NSColor *color)
                                                               @"GBRewind": @(kVK_Tab),
                                                               @"GBSlow-Motion": @(kVK_Shift),
 
-                                                              @"GBFilter": @"NearestNeighbor",
+                                                              @"GBFilter": @"Pixelated",
                                                               @"GBColorCorrection": @(GB_COLOR_CORRECTION_MODERN_BALANCED),
                                                               @"GBHighpassFilter": @(GB_HIGHPASS_ACCURATE),
                                                               @"GBRewindLength": @(120),

Cocoa/Preferences.xib

@@ -116,17 +116,23 @@
                 <popUpButton verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="6pP-kK-EEC" customClass="GBPreferencePopUpButton">
                     <rect key="frame" x="30" y="500" width="262" height="25"/>
                     <autoresizingMask key="autoresizingMask" widthSizable="YES" flexibleMinY="YES"/>
-                    <popUpButtonCell key="cell" type="push" title="Nearest neighbor (Pixelated)" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="proportionallyDown" inset="2" selectedItem="neN-eo-LA7" id="I1w-05-lGl">
+                    <popUpButtonCell key="cell" type="push" title="Nearest neighbor" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" borderStyle="borderAndBezel" imageScaling="proportionallyDown" inset="2" selectedItem="neN-eo-LA7" id="I1w-05-lGl">
                         <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                         <font key="font" metaFont="message"/>
                         <menu key="menu" id="xDC-0T-Qg9">
                             <items>
-                                <menuItem title="Nearest neighbor (Pixelated)" state="on" id="neN-eo-LA7" customClass="GBPreferenceMenuItem">
+                                <menuItem title="Nearest neighbor" id="neN-eo-LA7" customClass="GBPreferenceMenuItem">
                                     <modifierMask key="keyEquivalentModifierMask"/>
                                     <userDefinedRuntimeAttributes>
                                         <userDefinedRuntimeAttribute type="string" keyPath="preferenceValue" value="NearestNeighbor"/>
                                     </userDefinedRuntimeAttributes>
                                 </menuItem>
+                                <menuItem title="Pixelated" state="on" id="lSa-83-lEf" customClass="GBPreferenceMenuItem">
+                                    <modifierMask key="keyEquivalentModifierMask"/>
+                                    <userDefinedRuntimeAttributes>
+                                        <userDefinedRuntimeAttribute type="string" keyPath="preferenceValue" value="Pixelated"/>
+                                    </userDefinedRuntimeAttributes>
+                                </menuItem>
                                 <menuItem title="Bilinear (Blurry)" id="iDe-si-atu" customClass="GBPreferenceMenuItem">
                                     <userDefinedRuntimeAttributes>
                                         <userDefinedRuntimeAttribute type="string" keyPath="preferenceValue" value="Bilinear"/>

SDL/gui.c

@@ -1531,6 +1531,7 @@ struct shader_name {
 } shaders[] =
 {
     {"NearestNeighbor", "Nearest Neighbor"},
+    {"Pixelated", "Pixelated"},
     {"Bilinear", "Bilinear"},
     {"SmoothBilinear", "Smooth Bilinear"},
     {"MonoLCD", "Monochrome LCD"},
@@ -1557,7 +1558,6 @@ static void cycle_filter(unsigned index)
         }
     }
     
-
     i += 1;
     if (i >= sizeof(shaders) / sizeof(shaders[0])) {
         i -= sizeof(shaders) / sizeof(shaders[0]);
@@ -1566,7 +1566,7 @@ static void cycle_filter(unsigned index)
     strcpy(configuration.filter, shaders[i].file_name);
     free_shader(&shader);
     if (!init_shader_with_name(&shader, configuration.filter)) {
-        init_shader_with_name(&shader, "NearestNeighbor");
+        init_shader_with_name(&shader, "Pixelated");
     }
 }
 
@@ -1588,7 +1588,7 @@ static void cycle_filter_backwards(unsigned index)
     strcpy(configuration.filter, shaders[i].file_name);
     free_shader(&shader);
     if (!init_shader_with_name(&shader, configuration.filter)) {
-        init_shader_with_name(&shader, "NearestNeighbor");
+        init_shader_with_name(&shader, "Pixelated");
     }
 
 }
@@ -1603,7 +1603,7 @@ static const char *current_filter_name(unsigned index)
     }
     
     if (i == sizeof(shaders) / sizeof(shaders[0])) {
-        i = 0;
+        i = 1; // Pixelated
     }
     
     return shaders[i].display_name;

SDL/main.c

@@ -1596,7 +1596,7 @@ int main(int argc, char **argv)
     SDL_EventState(SDL_DROPFILE, SDL_ENABLE);
     
     if (!init_shader_with_name(&shader, configuration.filter)) {
-        init_shader_with_name(&shader, "NearestNeighbor");
+        init_shader_with_name(&shader, "Pixelated");
     }
     update_viewport();
     

Shaders/Pixelated.fsh

@@ -0,0 +1,18 @@
+STATIC vec4 scale(sampler2D image, vec2 position, vec2 input_resolution, vec2 output_resolution)
+{
+    vec2 scale_factor = output_resolution / input_resolution;
+    vec2 pixel = position * input_resolution - vec2(0.5, 0.5);
+    
+    vec4 q11 = texture(image, (floor(pixel) + 0.5) / input_resolution);
+    vec4 q12 = texture(image, (vec2(floor(pixel.x), ceil(pixel.y)) + 0.5) / input_resolution);
+    vec4 q21 = texture(image, (vec2(ceil(pixel.x), floor(pixel.y)) + 0.5) / input_resolution);
+    vec4 q22 = texture(image, (ceil(pixel) + 0.5) / input_resolution);
+    
+    vec2 t = fract(pixel);
+    vec2 w = clamp((t - 0.5) * scale_factor + 0.5, 0.0, 1.0);
+    
+    vec4 r1 = mix(q11, q21, w.x);
+    vec4 r2 = mix(q12, q22, w.x);
+    
+    return mix(r1, r2, w.y);
+}