Scaling filters in SDL

Makefile

@@ -43,7 +43,7 @@ endif
 # Set compilation and linkage flags based on target, platform and configuration
 
 CFLAGS += -Werror -Wall -std=gnu11 -ICore -D_GNU_SOURCE -DVERSION="$(VERSION)" -I. -D_USE_MATH_DEFINES
-SDL_LDFLAGS := -lSDL2
+SDL_LDFLAGS := -lSDL2 -lGL
 ifeq ($(PLATFORM),windows32)
 CFLAGS += -IWindows
 LDFLAGS += -lmsvcrt -lSDL2main -Wl,/MANIFESTFILE:NUL
@@ -56,7 +56,7 @@ SYSROOT := $(shell xcodebuild -sdk macosx -version Path 2> /dev/null)
 CFLAGS += -F/Library/Frameworks
 OCFLAGS += -x objective-c -fobjc-arc -Wno-deprecated-declarations -isysroot $(SYSROOT) -mmacosx-version-min=10.9
 LDFLAGS += -framework AppKit -framework PreferencePanes -framework Carbon -framework QuartzCore
-SDL_LDFLAGS := -F/Library/Frameworks -framework SDL2
+SDL_LDFLAGS := -F/Library/Frameworks -framework SDL2 -framework OpenGL
 endif
 CFLAGS += -Wno-deprecated-declarations
 ifeq ($(PLATFORM),windows32)
@@ -88,7 +88,7 @@ endif
 
 cocoa: $(BIN)/SameBoy.app
 quicklook: $(BIN)/SameBoy.qlgenerator
-sdl: $(SDL_TARGET) $(BIN)/SDL/dmg_boot.bin $(BIN)/SDL/cgb_boot.bin $(BIN)/SDL/LICENSE $(BIN)/SDL/registers.sym $(BIN)/SDL/background.bmp
+sdl: $(SDL_TARGET) $(BIN)/SDL/dmg_boot.bin $(BIN)/SDL/cgb_boot.bin $(BIN)/SDL/LICENSE $(BIN)/SDL/registers.sym $(BIN)/SDL/background.bmp $(BIN)/SDL/Shaders
 bootroms: $(BIN)/BootROMs/cgb_boot.bin $(BIN)/BootROMs/dmg_boot.bin
 tester: $(TESTER_TARGET) $(BIN)/tester/dmg_boot.bin $(BIN)/tester/cgb_boot.bin
 all: cocoa sdl tester
@@ -262,14 +262,21 @@ $(BIN)/SameBoy.app/Contents/Resources/%.bin: $(BOOTROMS_DIR)/%.bin
 	cp -f $^ $@
 	
 $(BIN)/SDL/LICENSE: LICENSE
+	-@$(MKDIR) -p $(dir $@)
 	cp -f $^ $@
 
 $(BIN)/SDL/registers.sym: Misc/registers.sym
+	-@$(MKDIR) -p $(dir $@)
 	cp -f $^ $@
 	
 $(BIN)/SDL/background.bmp: SDL/background.bmp
+	-@$(MKDIR) -p $(dir $@)
 	cp -f $^ $@
 
+$(BIN)/SDL/Shaders: Shaders
+	-@$(MKDIR) -p $(dir $@)
+	cp -rf $^ $@
+
 # Boot ROMs
 
 $(BIN)/BootROMs/%.bin: BootROMs/%.asm

SDL/gui.c

@@ -20,6 +20,31 @@ unsigned command_parameter;
 #define MODIFIER_NAME CTRL_STRING
 #endif
 
+shader_t shader;
+SDL_Rect rect;
+
+void render_texture(void *pixels,  void *previous)
+{
+    if (renderer) {
+        if (pixels) {
+            SDL_UpdateTexture(texture, NULL, pixels, 160 * sizeof (uint32_t));
+        }
+        SDL_RenderClear(renderer);
+        SDL_RenderCopy(renderer, texture, NULL, NULL);
+        SDL_RenderPresent(renderer);
+    }
+    else {
+        static void *_pixels = NULL;
+        if (pixels) {
+            _pixels = pixels;
+        }
+        glClearColor(0, 0, 0, 1);
+        glClear(GL_COLOR_BUFFER_BIT);
+        render_bitmap_with_shader(&shader, _pixels, previous, rect.x, rect.y, rect.w, rect.h);
+        SDL_GL_SwapWindow(window);
+    }
+}
+
 configuration_t configuration =
 {
     {   SDL_SCANCODE_RIGHT,
@@ -59,7 +84,7 @@ static const char *help[] ={
 void update_viewport(void)
 {
     int win_width, win_height;
-    SDL_GetWindowSize(window, &win_width, &win_height);
+    SDL_GL_GetDrawableSize(window, &win_width, &win_height);
     double x_factor = win_width / 160.0;
     double y_factor = win_height / 144.0;
     
@@ -80,10 +105,16 @@ void update_viewport(void)
     unsigned new_width = x_factor * 160;
     unsigned new_height = y_factor * 144;
     
-    SDL_Rect rect = (SDL_Rect){(win_width  - new_width) / 2, (win_height - new_height) /2,
+    rect = (SDL_Rect){(win_width  - new_width) / 2, (win_height - new_height) /2,
         new_width, new_height};
+    
+    if (renderer) {
         SDL_RenderSetViewport(renderer, &rect);
     }
+    else {
+        glViewport(rect.x, rect.y, rect.w, rect.h);
+    }
+}
 
 /* Does NOT check for bounds! */
 static void draw_char(uint32_t *buffer, unsigned char ch, uint32_t color)
@@ -234,9 +265,7 @@ void cycle_scaling(unsigned index)
         configuration.scaling_mode = 0;
     }
     update_viewport();
-    SDL_RenderClear(renderer);
+    render_texture(NULL, NULL);
-    SDL_RenderCopy(renderer, texture, NULL, NULL);
-    SDL_RenderPresent(renderer);
 }
 
 void cycle_scaling_backwards(unsigned index)
@@ -248,9 +277,7 @@ void cycle_scaling_backwards(unsigned index)
         configuration.scaling_mode--;
     }
     update_viewport();
-    SDL_RenderClear(renderer);
+    render_texture(NULL, NULL);
-    SDL_RenderCopy(renderer, texture, NULL, NULL);
-    SDL_RenderPresent(renderer);
 }
 
 static void cycle_color_correction(unsigned index)
@@ -273,6 +300,82 @@ static void cycle_color_correction_backwards(unsigned index)
     }
 }
 
+struct shader_name {
+    const char *file_name;
+    const char *display_name;
+} shaders[] =
+{
+    {"NearestNeighbor", "Nearest Neighbor"},
+    {"Bilinear", "Bilinear"},
+    {"SmoothBilinear", "Smooth Bilinear"},
+    {"Scale2x", "Scale2x"},
+    {"Scale4x", "Scale4x"},
+    {"AAScale2x", "Anti-aliased Scale2x"},
+    {"AAScale4x", "Anti-aliased Scale4x"},
+    {"HQ2x", "HQ2x"},
+    {"OmniScale", "OmniScale"},
+    {"OmniScaleLegacy", "OmniScale Legacy"},
+    {"AAOmniScaleLegacy", "AA OmniScale Legacy"},
+};
+
+static void cycle_filter(unsigned index)
+{
+    unsigned i = 0;
+    for (; i < sizeof(shaders) / sizeof(shaders[0]); i++) {
+        if (strcmp(shaders[i].file_name, configuration.filter) == 0) {
+            break;
+        }
+    }
+    
+
+    i += 1;
+    if (i >= sizeof(shaders) / sizeof(shaders[0])) {
+        i -= sizeof(shaders) / sizeof(shaders[0]);
+    }
+    
+    strcpy(configuration.filter, shaders[i].file_name);
+    free_shader(&shader);
+    if (!init_shader_with_name(&shader, configuration.filter)) {
+        init_shader_with_name(&shader, "NearestNeighbor");
+    }
+}
+
+static void cycle_filter_backwards(unsigned index)
+{
+    unsigned i = 0;
+    for (; i < sizeof(shaders) / sizeof(shaders[0]); i++) {
+        if (strcmp(shaders[i].file_name, configuration.filter) == 0) {
+            break;
+        }
+    }
+    
+    i -= 1;
+    if (i >= sizeof(shaders) / sizeof(shaders[0])) {
+        i = sizeof(shaders) / sizeof(shaders[0]) - 1;
+    }
+    
+    strcpy(configuration.filter, shaders[i].file_name);
+    free_shader(&shader);
+    if (!init_shader_with_name(&shader, configuration.filter)) {
+        init_shader_with_name(&shader, "NearestNeighbor");
+    }
+
+}
+const char *current_filter_name(unsigned index)
+{
+    unsigned i = 0;
+    for (; i < sizeof(shaders) / sizeof(shaders[0]); i++) {
+        if (strcmp(shaders[i].file_name, configuration.filter) == 0) {
+            break;
+        }
+    }
+    
+    if (i == sizeof(shaders) / sizeof(shaders[0])) {
+        i = 0;
+    }
+    
+    return shaders[i].display_name;
+}
 
 static void return_to_root_menu(unsigned index)
 {
@@ -282,6 +385,7 @@ static void return_to_root_menu(unsigned index)
 
 static const struct menu_item graphics_menu[] = {
     {"Scaling Mode:", cycle_scaling, current_scaling_mode, cycle_scaling_backwards},
+    {"Scaling Filter:", cycle_filter, current_filter_name, cycle_filter_backwards},
     {"Color Correction:", cycle_color_correction, current_color_correction_mode, cycle_color_correction_backwards},
     {"Back", return_to_root_menu},
     {NULL,}
@@ -399,6 +503,7 @@ static void detect_joypad_layout(unsigned index)
 static const struct menu_item joypad_menu[] = {
     {"Joypad:", cycle_joypads, current_joypad_name, cycle_joypads_backwards},
     {"Detect layout", detect_joypad_layout},
+    {"Back", return_to_root_menu},
     {NULL,}
 };
 
@@ -510,9 +615,7 @@ void run_gui(bool is_running)
             case SDL_WINDOWEVENT: {
                 if (event.window.event == SDL_WINDOWEVENT_RESIZED) {
                     update_viewport();
-                    SDL_RenderClear(renderer);
+                    render_texture(NULL, NULL);
-                    SDL_RenderCopy(renderer, texture, NULL, NULL);
-                    SDL_RenderPresent(renderer);
                 }
                 break;
             }
@@ -667,10 +770,7 @@ void run_gui(bool is_running)
                     break;
             }
             
-            SDL_UpdateTexture(texture, NULL, pixels, 160 * sizeof (uint32_t));
+            render_texture(pixels, NULL);
-            SDL_RenderClear(renderer);
-            SDL_RenderCopy(renderer, texture, NULL, NULL);
-            SDL_RenderPresent(renderer);
         }
     } while (SDL_WaitEvent(&event));
 }

SDL/gui.h

@@ -3,11 +3,13 @@
 
 #include <SDL2/SDL.h>
 #include <Core/gb.h>
+#include "shader.h"
 
 extern SDL_Window *window;
 extern SDL_Renderer *renderer;
 extern SDL_Texture *texture;
 extern SDL_PixelFormat *pixel_format;
+extern shader_t shader;
 
 enum scaling_mode {
     GB_SDL_SCALING_ENTIRE_WINDOW,
@@ -37,6 +39,8 @@ typedef struct {
     bool div_joystick;
     bool flip_joystick_bit_1;
     bool swap_joysticks_bits_1_and_2;
+    
+    char filter[32];
 } configuration_t;
 
 extern configuration_t configuration;
@@ -44,5 +48,6 @@ extern configuration_t configuration;
 void update_viewport(void);
 void run_gui(bool is_running);
 unsigned fix_joypad_button(unsigned button);
+void render_texture(void *pixels, void *previous);
 
 #endif

SDL/main.c

@@ -4,6 +4,7 @@
 #include "gb.h"
 #include "utils.h"
 #include "gui.h"
+#include "shader.h"
 
 #ifndef _WIN32
 #define AUDIO_FREQUENCY 96000
@@ -212,10 +213,7 @@ static void handle_events(GB_gameboy_t *gb)
 
 static void vblank(GB_gameboy_t *gb)
 {
-    SDL_UpdateTexture(texture, NULL, pixels, 160 * sizeof (uint32_t));
+    render_texture(pixels, NULL);
-    SDL_RenderClear(renderer);
-    SDL_RenderCopy(renderer, texture, NULL, NULL);
-    SDL_RenderPresent(renderer);
     handle_events(gb);
 }
 
@@ -390,14 +388,24 @@ usage:
 
     SDL_Init( SDL_INIT_EVERYTHING );
     
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+
     window = SDL_CreateWindow("SameBoy v" xstr(VERSION), SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
-                              160 * 2, 144 * 2, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
+                              160 * 2, 144 * 2, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     SDL_SetWindowMinimumSize(window, 160, 144);
+    
+    SDL_GLContext gl_context = SDL_GL_CreateContext(window);
+    if (gl_context == NULL) {
         renderer = SDL_CreateRenderer(window, -1, 0);
-    
         texture = SDL_CreateTexture(renderer, SDL_GetWindowPixelFormat(window), SDL_TEXTUREACCESS_STREAMING, 160, 144);
-    
         pixel_format = SDL_AllocFormat(SDL_GetWindowPixelFormat(window));
+    }
+    else {
+        pixel_format = SDL_AllocFormat(SDL_PIXELFORMAT_ABGR8888);
+    }
+    
     
     /* Configure Audio */
     memset(&want_aspec, 0, sizeof(want_aspec));
@@ -420,6 +428,11 @@ usage:
 
     SDL_EventState(SDL_DROPFILE, SDL_ENABLE);
     
+    if (!init_shader_with_name(&shader, configuration.filter)) {
+        init_shader_with_name(&shader, "NearestNeighbor");
+    }
+    update_viewport();
+    
     if (filename == NULL) {
         run_gui(false);
     }

SDL/shader.c

@@ -0,0 +1,184 @@
+#include <stdio.h>
+#include <string.h>
+#include "shader.h"
+#include "utils.h"
+#include <OpenGL/gl3.h>
+
+static const char *vertex_shader = "\n\
+#version 150 \n\
+in vec4 aPosition;\n\
+void main(void) {\n\
+gl_Position = aPosition;\n\
+}\n\
+";
+
+static GLuint create_shader(const char *source, GLenum type)
+{
+    // Create the shader object
+    GLuint shader = glCreateShader(type);
+    // Load the shader source
+    glShaderSource(shader, 1, &source, 0);
+    // Compile the shader
+    glCompileShader(shader);
+    // Check for errors
+    GLint status = 0;
+    glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
+    if (status == GL_FALSE) {
+        GLchar messages[1024];
+        glGetShaderInfoLog(shader, sizeof(messages), 0, &messages[0]);
+        fprintf(stderr, "GLSL Shader Error: %s", messages);
+    }
+    return shader;
+}
+
+static GLuint create_program(const char *vsh, const char *fsh)
+{
+    // Build shaders
+    GLuint vertex_shader = create_shader(vsh, GL_VERTEX_SHADER);
+    GLuint fragment_shader = create_shader(fsh, GL_FRAGMENT_SHADER);
+    
+    // Create program
+    GLuint program = glCreateProgram();
+    
+    // Attach shaders
+    glAttachShader(program, vertex_shader);
+    glAttachShader(program, fragment_shader);
+    
+    // Link program
+    glLinkProgram(program);
+    // Check for errors
+    GLint status;
+    glGetProgramiv(program, GL_LINK_STATUS, &status);
+    
+    if (status == GL_FALSE) {
+        GLchar messages[1024];
+        glGetProgramInfoLog(program, sizeof(messages), 0, &messages[0]);
+        fprintf(stderr, "GLSL Program Error: %s", messages);
+    }
+    
+    // Delete shaders
+    glDeleteShader(vertex_shader);
+    glDeleteShader(fragment_shader);
+    
+    return program;
+}
+
+bool init_shader_with_name(shader_t *shader, const char *name)
+{
+    static char master_shader_code[0x801] = {0,};
+    static char shader_code[0x10001] = {0,};
+    static char final_shader_code[0x10801] = {0,};
+    static ssize_t filter_token_location = 0;
+    
+    if (!master_shader_code[0]) {
+        FILE *master_shader_f = fopen(executable_relative_path("Shaders/MasterShader.fsh"), "r");
+        if (!master_shader_f) return false;
+        fread(master_shader_code, 1, sizeof(master_shader_code) - 1, master_shader_f);
+        fclose(master_shader_f);
+        filter_token_location = strstr(master_shader_code, "{filter}") - master_shader_code;
+        if (filter_token_location < 0) {
+            master_shader_code[0] = 0;
+            return false;
+        }
+    }
+    
+    char shader_path[1024];
+    sprintf(shader_path, "Shaders/%s.fsh", name);
+    
+    FILE *shader_f = fopen(executable_relative_path(shader_path), "r");
+    if (!shader_f) return false;
+    memset(shader_code, 0, sizeof(shader_code));
+    fread(shader_code, 1, sizeof(shader_code) - 1, shader_f);
+    fclose(shader_f);
+    
+    memset(final_shader_code, 0, sizeof(final_shader_code));
+    memcpy(final_shader_code, master_shader_code, filter_token_location);
+    strcpy(final_shader_code + filter_token_location, shader_code);
+    strcat(final_shader_code + filter_token_location,
+           master_shader_code + filter_token_location + sizeof("{filter}") - 1);
+    
+    shader->program = create_program(vertex_shader, final_shader_code);
+    
+    // Attributes
+    shader->position_attribute = glGetAttribLocation(shader->program, "aPosition");
+    // Uniforms
+    shader->resolution_uniform = glGetUniformLocation(shader->program, "uResolution");
+    shader->origin_uniform = glGetUniformLocation(shader->program, "uOrigin");
+
+    glGenTextures(1, &shader->texture);
+    glBindTexture(GL_TEXTURE_2D, shader->texture);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glBindTexture(GL_TEXTURE_2D, 0);
+    shader->texture_uniform = glGetUniformLocation(shader->program, "image");
+    
+    glGenTextures(1, &shader->previous_texture);
+    glBindTexture(GL_TEXTURE_2D, shader->previous_texture);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glBindTexture(GL_TEXTURE_2D, 0);
+    shader->previous_texture_uniform = glGetUniformLocation(shader->program, "previousImage");
+    
+    shader->mix_previous_uniform = glGetUniformLocation(shader->program, "uMixPrevious");
+    
+    // Program
+    
+    glUseProgram(shader->program);
+    
+    GLuint vao;
+    glGenVertexArrays(1, &vao);
+    glBindVertexArray(vao);
+    
+    GLuint vbo;
+    glGenBuffers(1, &vbo);
+    
+    // Attributes
+    
+    
+    static GLfloat const quad[16] = {
+        -1.f, -1.f, 0, 1,
+        -1.f, +1.f, 0, 1,
+        +1.f, -1.f, 0, 1,
+        +1.f, +1.f, 0, 1,
+    };
+    
+    
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(quad), quad, GL_STATIC_DRAW);
+    glEnableVertexAttribArray(shader->position_attribute);
+    glVertexAttribPointer(shader->position_attribute, 4, GL_FLOAT, GL_FALSE, 0, 0);
+    
+    return true;
+}
+
+void render_bitmap_with_shader(shader_t *shader, void *bitmap, void *previous,unsigned x, unsigned y, unsigned w, unsigned h)
+{
+    glUseProgram(shader->program);
+    glUniform2f(shader->origin_uniform, x, y);
+    glUniform2f(shader->resolution_uniform, w, h);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, shader->texture);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 160, 144, 0, GL_RGBA, GL_UNSIGNED_BYTE, bitmap);
+    glUniform1i(shader->texture_uniform, 0);
+    glUniform1i(shader->mix_previous_uniform, previous != NULL);
+    if (previous) {
+        glActiveTexture(GL_TEXTURE1);
+        glBindTexture(GL_TEXTURE_2D, shader->previous_texture);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 160, 144, 0, GL_RGBA, GL_UNSIGNED_BYTE, previous);
+        glUniform1i(shader->previous_texture_uniform, 1);
+    }
+    glBindFragDataLocation(shader->program, 0, "frag_color");
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+}
+
+void free_shader(shader_t *shader)
+{
+    glDeleteProgram(shader->program);
+    glDeleteTextures(1, &shader->texture);
+    glDeleteTextures(1, &shader->previous_texture);
+
+}

SDL/shader.h

@@ -0,0 +1,23 @@
+#ifndef shader_h
+#define shader_h
+#include <OpenGL/gl3.h>
+#include <stdbool.h>
+
+typedef struct shader_s {
+    GLuint resolution_uniform;
+    GLuint origin_uniform;
+    GLuint texture_uniform;
+    GLuint previous_texture_uniform;
+    GLuint mix_previous_uniform;
+    
+    GLuint position_attribute;
+    GLuint texture;
+    GLuint previous_texture;
+    GLuint program;
+} shader_t;
+
+bool init_shader_with_name(shader_t *shader, const char *name);
+void render_bitmap_with_shader(shader_t *shader, void *bitmap, void *previous,unsigned x, unsigned y, unsigned w, unsigned h);
+void free_shader(struct shader_s *shader);
+
+#endif /* shader_h */

Shaders/MasterShader.fsh

@@ -4,14 +4,20 @@ uniform sampler2D previousImage;
 uniform bool uMixPrevious;
 
 uniform vec2 uResolution;
+uniform vec2 uOrigin;
 const vec2 textureDimensions = vec2(160, 144);
 
 out vec4 frag_color;
 
+vec4 modified_frag_cord;
+#define gl_FragCoord modified_frag_cord
 #line 1
 {filter}
+#undef gl_FragCoord
 
 void main() {
+    modified_frag_cord = gl_FragCoord - vec4(uOrigin.x, uOrigin.y, 0, 0);
+    
     if (uMixPrevious) {
         frag_color = mix(scale(image), scale(previousImage), 0.5);
     }