feat: add rasterization primitives

.clang-format

@@ -0,0 +1,5 @@
+BasedOnStyle: LLVM
+ColumnLimit: 80
+BreakBeforeBraces: Attach
+IndentWidth: 2
+ContinuationIndentWidth: 4

.gitignore

@@ -1,7 +1,9 @@
 .DS_Store
+.vscode
 .idea
 *.log
 tmp/
 .cache/
 build/
 .direnv/
+*.ppm

.vscode/c_cpp_properties.json

@@ -1,19 +0,0 @@
-{
-    "configurations": [
-        {
-            "name": "Linux",
-            "includePath": [
-                "${workspaceFolder}/**"
-            ],
-            "defines": [],
-            "compilerPath": "/usr/bin/gcc",
-            "cStandard": "c17",
-            "cppStandard": "gnu++17",
-            "intelliSenseMode": "linux-gcc-x64",
-            "compileCommands": [
-                "${workspaceFolder}/build/compile_commands.json"
-            ]
-        }
-    ],
-    "version": 4
-}

flake.lock

@@ -1,27 +1,23 @@
 {
-  "nodes": {
-    "nixpkgs": {
-      "locked": {
-        "lastModified": 1772433332,
-        "narHash": "sha256-izhTDFKsg6KeVBxJS9EblGeQ8y+O8eCa6RcW874vxEc=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "cf59864ef8aa2e178cccedbe2c178185b0365705",
-        "type": "github"
+  "nodes" : {
+    "nixpkgs" : {
+      "locked" : {
+        "lastModified" : 1772433332,
+        "narHash" : "sha256-izhTDFKsg6KeVBxJS9EblGeQ8y+O8eCa6RcW874vxEc=",
+        "owner" : "NixOS",
+        "repo" : "nixpkgs",
+        "rev" : "cf59864ef8aa2e178cccedbe2c178185b0365705",
+        "type" : "github"
       },
-      "original": {
-        "owner": "NixOS",
-        "ref": "nixos-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
+      "original" : {
+        "owner" : "NixOS",
+        "ref" : "nixos-unstable",
+        "repo" : "nixpkgs",
+        "type" : "github"
       }
     },
-    "root": {
-      "inputs": {
-        "nixpkgs": "nixpkgs"
-      }
-    }
+    "root" : {"inputs" : {"nixpkgs" : "nixpkgs"}}
   },
-  "root": "root",
-  "version": 7
+  "root" : "root",
+  "version" : 7
 }

flake.nix

@@ -3,30 +3,23 @@
 
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
 
-  outputs =
-    {
+  outputs = {
       self,
       nixpkgs,
-    }:
-    let
-      system = "x86_64-linux";
+  } : let system = "x86_64-linux";
   pkgs = import nixpkgs { inherit system; };
-    in
-    {
+  in {
     devShells.${system}.default = pkgs.mkShell {
-        nativeBuildInputs = with pkgs; [
-          gcc
-          clang-tools
-          lldb
+      nativeBuildInputs = with pkgs;
+      [gcc clang -
+          tools lldb
 
-          meson
-          ninja
-          pkg-config
+              meson ninja pkg -
+          config
 
               gtk4
 
-          gdb
-        ];
+                  gdb];
 
       shellHook = "";
     };

meson.build

@@ -14,7 +14,9 @@ gtk = dependency('gtk4', required: true)
 
 src = files(
   'src/main.c',
-  'src/matrix.c',
+  'src/core/matrix.c',
+  'src/core/primitives.c',
+  'src/core/raster.c',
   'src/ui/uicontroller.c',
   'src/ui/vektorcanvas.c'
 )

src/core/matrix.c

@@ -1,6 +1,8 @@
 #include "matrix.h"
 #include <math.h>
 
+inline M33 m33_zero(void) { return (M33){{{0, 0, 0}, {0, 0, 0}, {0, 0, 0}}}; }
+
 inline M33 m33_identity(void) {
   return (M33){{{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}};
 }
@@ -18,6 +20,10 @@ inline M33 m33_rotate(double theta) {
       {{cos(theta), -sin(theta), 0}, {sin(theta), cos(theta), 0}, {0, 0, 1}}};
 }
 
+inline M33 m33_shear(double theta_x, double theta_y) {
+  return (M33){{{1, tan(theta_x), 0}, {tan(theta_y), 1, 0}, {0, 0, 0}}};
+}
+
 M33 m33_add(const M33 m1, const M33 m2) {
   M33 res;
   for (int i = 0; i < 3; ++i)

src/core/matrix.h

@@ -12,6 +12,7 @@ M33 m33_identity(void);
 M33 m33_translate(double tx, double ty);
 M33 m33_scale(double sx, double sy);
 M33 m33_rotate(double rad);
+M33 m33_shear(double theta_x, double theta_y);
 
 M33 m33_add(const M33 m1, const M33 m2);
 M33 m33_sub(const M33 m1, const M33 m2);

src/core/primitives.c

@@ -0,0 +1,47 @@
+#include "primitives.h"
+
+Polyline *mk_polyline(void) {
+  Polyline *pl = malloc(sizeof(Polyline));
+  pl->count = 0;
+  pl->capacity = 4;
+  pl->points = malloc(sizeof(V2) * pl->capacity);
+  return pl;
+}
+
+void add_point_polyline(Polyline *pl, V2 point) {
+  if (pl->count >= pl->capacity) {
+    pl->capacity *= 2;
+    pl->points = realloc(pl->points, sizeof(V2) * pl->capacity);
+  }
+  pl->points[pl->count++] = point;
+}
+
+void free_polyline(Polyline *pl) {
+  if (!pl)
+    return;
+  free(pl->points);
+  free(pl);
+}
+
+Polygon *mk_polygon(void) {
+  Polygon *pg = malloc(sizeof(Polygon));
+  pg->count = 0;
+  pg->capacity = 4;
+  pg->points = malloc(sizeof(V2) * pg->capacity);
+  return pg;
+}
+
+void add_point_polygon(Polygon *pg, V2 point) {
+  if (pg->count >= pg->capacity) {
+    pg->capacity *= 2;
+    pg->points = realloc(pg->points, sizeof(V2) * pg->capacity);
+  }
+  pg->points[pg->count++] = point;
+}
+
+void free_polygon(Polygon *pg) {
+  if (!pg)
+    return;
+  free(pg->points);
+  free(pg);
+}

src/core/primitives.h

@@ -0,0 +1,50 @@
+#ifndef PRIMITIVES_H_
+#define PRIMITIVES_H_
+
+#include "stddef.h"
+#include "stdlib.h"
+#include "vector.h"
+
+typedef struct {
+  V2 p1;
+  V2 p2;
+} Line;
+
+typedef struct {
+  V2 *points;
+  size_t count;
+  size_t capacity;
+} Polyline;
+
+typedef struct {
+  V2 *points;
+  size_t count;
+  size_t capacity;
+} Polygon;
+
+typedef struct {
+  V2 center;
+  double radius;
+} Circle;
+
+typedef enum { LINE, POLYLINE, POLYGON, CIRCLE } PrimitiveKind;
+
+typedef struct {
+  PrimitiveKind kind;
+  union {
+    Line line;
+    Polyline *polyline;
+    Polygon *polygon;
+    Circle circle;
+  };
+} Primitive;
+
+Polyline *mk_polyline(void);
+void add_point_polyline(Polyline *pl, V2 point);
+void free_polyline(Polyline *pl);
+
+Polygon *mk_polygon(void);
+void add_point_polygon(Polygon *pl, V2 point);
+void free_polygon(Polygon *pl);
+
+#endif // PRIMITIVES_H_

src/core/raster.c

@@ -0,0 +1,80 @@
+#include "raster.h"
+#include "primitives.h"
+#include "stddef.h"
+
+void add_edge(EdgeBuffer *buffer, Edge edge) {
+  if (buffer->count >= buffer->capacity) {
+    buffer->capacity = buffer->capacity ? buffer->capacity * 2 : 4;
+    buffer->edges = realloc(buffer->edges, sizeof(Edge) * buffer->capacity);
+  }
+  buffer->edges[buffer->count++] = edge;
+}
+
+void flatten_line(EdgeBuffer *buffer, Line line) {
+  add_edge(buffer, (Edge){line.p1, line.p2, 0});
+}
+
+void flatten_polyline(EdgeBuffer *buffer, Polyline *line) {
+  for (size_t i = 0; i + 1 < line->count; i++) {
+    add_edge(buffer, (Edge){line->points[i], line->points[i + 1], 0});
+  }
+}
+
+void flatten_polygon(EdgeBuffer *buffer, Polygon *pg) {
+  size_t n = pg->count;
+  if (n < 3)
+    return;
+
+  for (size_t i = 0; i < n; i++) {
+    V2 p1 = pg->points[i];
+    V2 p2 = pg->points[(i + 1) % n];
+    int winding = (p1.y < p2.y) ? +1 : -1;
+    add_edge(buffer, (Edge){p1, p2, winding});
+  }
+}
+
+inline Framebuffer mk_framebuffer(unsigned int W, unsigned int H) {
+  Framebuffer fb = {.width = W, .height = H, .pixels = calloc(W * H * 3, 1)};
+  return fb;
+}
+
+inline void put_pixel(Framebuffer *fb, int x, int y, unsigned char r,
+                      unsigned char g, unsigned char b) {
+  if ((unsigned)x >= fb->width || (unsigned)y >= fb->height)
+    return;
+
+  int i = (y * fb->width + x) * 3;
+  fb->pixels[i + 0] = r;
+  fb->pixels[i + 1] = g;
+  fb->pixels[i + 2] = b;
+}
+
+void draw_line(Framebuffer *fb, V2 a, V2 b, unsigned char r, unsigned char g,
+               unsigned char bl) {
+  int x0 = (int)a.x;
+  int y0 = (int)a.y;
+  int x1 = (int)b.x;
+  int y1 = (int)b.y;
+
+  int dx = abs(x1 - x0);
+  int sx = x0 < x1 ? 1 : -1;
+  int dy = -abs(y1 - y0);
+  int sy = y0 < y1 ? 1 : -1;
+  int err = dx + dy;
+
+  for (;;) {
+    put_pixel(fb, x0, y0, r, g, bl);
+    if (x0 == x1 && y0 == y1)
+      break;
+
+    int e2 = 2 * err;
+    if (e2 >= dy) {
+      err += dy;
+      x0 += sx;
+    }
+    if (e2 <= dx) {
+      err += dx;
+      y0 += sy;
+    }
+  }
+}

src/core/raster.h

@@ -0,0 +1,40 @@
+#ifndef RASTER_H_
+#define RASTER_H_
+
+#include "primitives.h"
+#include "stddef.h"
+#include "vector.h"
+
+typedef struct {
+  V2 p1;
+  V2 p2;
+  int winding;
+} Edge;
+
+typedef struct {
+  Edge *edges;
+  size_t count;
+  size_t capacity;
+} EdgeBuffer;
+
+void add_edge(EdgeBuffer *edges, Edge edge);
+
+void flatten_line(EdgeBuffer *edges, Line line);
+void flatten_polyline(EdgeBuffer *edges, Polyline *line);
+void flatten_polygon(EdgeBuffer *buffer, Polygon *line);
+
+typedef struct {
+  unsigned int width;
+  unsigned int height;
+  unsigned char *pixels; // Flat RGB8 array
+} Framebuffer;
+
+Framebuffer mk_framebuffer(unsigned int width, unsigned int height);
+
+void put_pixel(Framebuffer *fb, int x, int y, unsigned char r, unsigned char g,
+               unsigned char b);
+
+void draw_line(Framebuffer *fb, V2 a, V2 b, unsigned char r, unsigned char g,
+               unsigned char bl);
+
+#endif // RASTER_H_

src/core/vector.h

@@ -8,6 +8,16 @@ typedef struct {
   double y;
 } V2;
 
+typedef struct {
+  double x;
+  double y;
+  double z;
+} V3;
+
+static inline V3 vec2_vector(const V2 v) { return (V3){v.x, v.y, 0}; }
+
+static inline V3 vec2_point(const V2 v) { return (V3){v.x, v.y, 1}; }
+
 static inline V2 vec2_add(const V2 v1, const V2 v2) {
   return (V2){v1.x + v2.x, v1.y + v2.y};
 }

src/main.c

@@ -2,31 +2,58 @@
 #include "stdio.h"
 #include "stdlib.h"
 
+#include "./core/raster.h"
 #include "./ui/uicontroller.h"
 #include "./ui/vektorcanvas.h"
 
-
-static void on_map(GtkWidget* window, gpointer user_data) {
-  vektor_uictrl_map((VektorWidgetState*)user_data);
+static void on_map(GtkWidget *window, gpointer user_data) {
+  vektor_uictrl_map((VektorWidgetState *)user_data);
 }
 
 static void activate(GtkApplication *app, gpointer user_data) {
 
-  VektorWidgetState* widget_state = (VektorWidgetState*)malloc(sizeof(VektorWidgetState));
+  VektorWidgetState *widget_state =
+      (VektorWidgetState *)malloc(sizeof(VektorWidgetState));
   vektor_uictrl_init(app, widget_state);
 
-  VektorCanvas* canvas = (VektorCanvas*)malloc(sizeof(VektorCanvas));
+  VektorCanvas *canvas = (VektorCanvas *)malloc(sizeof(VektorCanvas));
   vektor_canvas_init(widget_state, canvas);
   VektorCanvasColor red = vektor_color_new(255, 0, 0, 255);
   vektor_canvas_fill(canvas, &red);
   vektor_canvas_update(canvas);
 
-  g_signal_connect(widget_state->window, "map", G_CALLBACK(on_map), widget_state);
+  g_signal_connect(widget_state->window, "map", G_CALLBACK(on_map),
+                   widget_state);
 
   gtk_window_present(widget_state->window);
 }
 
+void write_ppm(const char *path, const Framebuffer *fb) {
+  FILE *f = fopen(path, "wb");
+  if (!f)
+    abort();
+
+  fprintf(f, "P6\n%d %d\n255\n", fb->width, fb->height);
+  fwrite(fb->pixels, 1, fb->width * fb->height * 3, f);
+  fclose(f);
+}
+
 int main(int argc, char **argv) {
+  Framebuffer fb = mk_framebuffer(256, 256);
+  EdgeBuffer edges = {0};
+
+  Polygon pg = *mk_polygon();
+  add_point_polygon(&pg, (V2){50, 50});
+  add_point_polygon(&pg, (V2){200, 80});
+  add_point_polygon(&pg, (V2){120, 200});
+
+  flatten_polygon(&edges, &pg);
+
+  for (size_t i = 0; i < edges.count; i++) {
+    draw_line(&fb, edges.edges[i].p1, edges.edges[i].p2, 255, 255, 255);
+  }
+
+  write_ppm("out.ppm", &fb);
 
   GtkApplication *app;
   int status;

src/ui/uicontroller.c

@@ -1,20 +1,22 @@
 #include "uicontroller.h"
 #include "gtk/gtk.h"
 
-void vektor_uictrl_init(GtkApplication* app, VektorWidgetState* stateOut) {
-    GtkBuilder* builder = gtk_builder_new();
-    GError* error = NULL;
+void vektor_uictrl_init(GtkApplication *app, VektorWidgetState *stateOut) {
+  GtkBuilder *builder = gtk_builder_new();
+  GError *error = NULL;
 
   g_print("%s\n", g_get_current_dir());
 
   // TODO: .ui files as resources instead of sketchy relative paths
-    if(!gtk_builder_add_from_file(builder, "./ui/main.ui", &error)) {
+  if (!gtk_builder_add_from_file(builder, "./ui/main.ui", &error)) {
     g_error("Fatal: %s", error->message);
   }
 
   stateOut->window = GTK_WINDOW(gtk_builder_get_object(builder, "main_window"));
-    stateOut->workspacePaned = GTK_PANED(gtk_builder_get_object(builder, "workspace_paned"));
-    stateOut->workspaceCanvas = GTK_PICTURE(gtk_builder_get_object(builder, "workspace"));
+  stateOut->workspacePaned =
+      GTK_PANED(gtk_builder_get_object(builder, "workspace_paned"));
+  stateOut->workspaceCanvas =
+      GTK_PICTURE(gtk_builder_get_object(builder, "workspace"));
 
   gtk_window_set_application(stateOut->window, app);
   gtk_window_set_title(stateOut->window, "Vektor");
@@ -23,7 +25,7 @@ void vektor_uictrl_init(GtkApplication* app, VektorWidgetState* stateOut) {
   g_object_unref(builder);
 }
 
-void vektor_uictrl_map(VektorWidgetState* state) {
+void vektor_uictrl_map(VektorWidgetState *state) {
 
   // set the workspace divider to 7:3 ratio
   int window_width = gtk_widget_get_width(GTK_WIDGET(state->window));

src/ui/uicontroller.h

@@ -8,14 +8,14 @@ Global application widget state, holding references to
 all the widgets used in internal logic of the program
 */
 typedef struct VektorWidgetState {
-    GtkWindow* window;
-    GtkPaned* workspacePaned;
-    GtkPicture* workspaceCanvas;
+  GtkWindow *window;
+  GtkPaned *workspacePaned;
+  GtkPicture *workspaceCanvas;
 
-    //GtkWidget* Workspace
+  // GtkWidget* Workspace
 } VektorWidgetState;
 
-void vektor_uictrl_init(GtkApplication* app, VektorWidgetState* stateOut);
-void vektor_uictrl_map(VektorWidgetState* state);
+void vektor_uictrl_init(GtkApplication *app, VektorWidgetState *stateOut);
+void vektor_uictrl_map(VektorWidgetState *state);
 
 #endif

src/ui/vektorcanvas.c

@@ -1,65 +1,57 @@
 #include "gtk/gtk.h"
 
-#include "vektorcanvas.h"
 #include "uicontroller.h"
+#include "vektorcanvas.h"
 
 #define VKTR_CANVAS_WIDTH 400
 #define VKTR_CANVAS_HEIGHT 400
 #define VKTR_CANVAS_SIZE (VKTR_CANVAS_WIDTH * VKTR_CANVAS_HEIGHT * 4)
 
-void vektor_canvas_init(VektorWidgetState* state, VektorCanvas* canvasOut) {
+void vektor_canvas_init(VektorWidgetState *state, VektorCanvas *canvasOut) {
   canvasOut->canvasWidget = state->workspaceCanvas;
   canvasOut->width = VKTR_CANVAS_WIDTH;
   canvasOut->height = VKTR_CANVAS_HEIGHT;
   canvasOut->canvasPixels = g_malloc0(VKTR_CANVAS_SIZE);
 
-    canvasOut->canvasPixelBytes = g_bytes_new(canvasOut->canvasPixels, VKTR_CANVAS_SIZE);
+  canvasOut->canvasPixelBytes =
+      g_bytes_new(canvasOut->canvasPixels, VKTR_CANVAS_SIZE);
   canvasOut->canvasTexture = gdk_memory_texture_new(
-        VKTR_CANVAS_WIDTH,
-        VKTR_CANVAS_HEIGHT,
-        GDK_MEMORY_R8G8B8A8,
-        canvasOut->canvasPixelBytes,
-        VKTR_CANVAS_WIDTH * 4
-    );
+      VKTR_CANVAS_WIDTH, VKTR_CANVAS_HEIGHT, GDK_MEMORY_R8G8B8A8,
+      canvasOut->canvasPixelBytes, VKTR_CANVAS_WIDTH * 4);
 
-    gtk_picture_set_paintable(canvasOut->canvasWidget, GDK_PAINTABLE(canvasOut->canvasTexture));
+  gtk_picture_set_paintable(canvasOut->canvasWidget,
+                            GDK_PAINTABLE(canvasOut->canvasTexture));
 
-    //g_object_unref(bytes);
+  // g_object_unref(bytes);
 }
 
-void vektor_canvas_update(VektorCanvas* canvas) {
+void vektor_canvas_update(VektorCanvas *canvas) {
   g_bytes_unref(canvas->canvasPixelBytes);
-    canvas->canvasPixelBytes = g_bytes_new(canvas->canvasPixels, VKTR_CANVAS_SIZE);
+  canvas->canvasPixelBytes =
+      g_bytes_new(canvas->canvasPixels, VKTR_CANVAS_SIZE);
 
   g_object_unref(canvas->canvasTexture);
-    canvas->canvasTexture = gdk_memory_texture_new(
-        canvas->width, canvas->height,
-        GDK_MEMORY_R8G8B8A8,
-        canvas->canvasPixelBytes,
-        canvas->width * 4
-    );
+  canvas->canvasTexture =
+      gdk_memory_texture_new(canvas->width, canvas->height, GDK_MEMORY_R8G8B8A8,
+                             canvas->canvasPixelBytes, canvas->width * 4);
 
-    gtk_picture_set_paintable(canvas->canvasWidget, GDK_PAINTABLE(canvas->canvasTexture));
+  gtk_picture_set_paintable(canvas->canvasWidget,
+                            GDK_PAINTABLE(canvas->canvasTexture));
 }
 
-void vektor_canvas_fill(VektorCanvas* canvas, VektorCanvasColor* color) {
-    for(int x = 0; x < VKTR_CANVAS_WIDTH; x++) {
-        for(int y = 0; y < VKTR_CANVAS_HEIGHT; y++) {
+void vektor_canvas_fill(VektorCanvas *canvas, VektorCanvasColor *color) {
+  for (int x = 0; x < VKTR_CANVAS_WIDTH; x++) {
+    for (int y = 0; y < VKTR_CANVAS_HEIGHT; y++) {
       int i = (y * VKTR_CANVAS_WIDTH + x) * 4;
-            canvas->canvasPixels[i+0] = color->r;
-            canvas->canvasPixels[i+1] = color->g;
-            canvas->canvasPixels[i+2] = color->b;
-            canvas->canvasPixels[i+3] = color->a;
+      canvas->canvasPixels[i + 0] = color->r;
+      canvas->canvasPixels[i + 1] = color->g;
+      canvas->canvasPixels[i + 2] = color->b;
+      canvas->canvasPixels[i + 3] = color->a;
     }
   }
 }
 
 VektorCanvasColor vektor_color_new(guchar cr, guchar cg, guchar cb, guchar ca) {
-    VektorCanvasColor c = {
-        .r = cr,
-        .g = cg,
-        .b = cb,
-        .a = ca
-    };
+  VektorCanvasColor c = {.r = cr, .g = cg, .b = cb, .a = ca};
   return c;
 }

src/ui/vektorcanvas.h

@@ -4,12 +4,12 @@
 #include "uicontroller.h"
 
 typedef struct VektorCanvas {
-    GtkPicture* canvasWidget;
+  GtkPicture *canvasWidget;
 
   // texture related stuff
-    guchar* canvasPixels;
-    GdkTexture* canvasTexture;
-    GBytes* canvasPixelBytes;
+  guchar *canvasPixels;
+  GdkTexture *canvasTexture;
+  GBytes *canvasPixelBytes;
 
   int width;
   int height;
@@ -22,9 +22,9 @@ typedef struct VektorCanvasColor {
   guchar a;
 } VektorCanvasColor;
 
-void vektor_canvas_init(VektorWidgetState* state, VektorCanvas* canvasOut);
-void vektor_canvas_update(VektorCanvas* canvas);
-void vektor_canvas_fill(VektorCanvas* canvas, VektorCanvasColor* color);
+void vektor_canvas_init(VektorWidgetState *state, VektorCanvas *canvasOut);
+void vektor_canvas_update(VektorCanvas *canvas);
+void vektor_canvas_fill(VektorCanvas *canvas, VektorCanvasColor *color);
 
 VektorCanvasColor vektor_color_new(guchar r, guchar g, guchar b, guchar a);