feat: add circles

src/application/applicationstate.c

@@ -220,6 +220,13 @@ void vektor_appstate_new(VektorWidgetState* wstate, VektorAppState* stateOut) {
 
     stateOut->shapeBuffer = malloc(sizeof(VektorShapeBuffer));
     *stateOut->shapeBuffer = (VektorShapeBuffer){0};
+
+    VektorCircle circ = (VektorCircle){.center = (V2){0, 0}, .radius = 0.3};
+    VektorShape shp = vektor_shape_new(
+        (VektorPrimitive){.kind = VEKTOR_CIRCLE, .circle = circ},
+        (VektorStyle){.stroke_color = stateOut->currentColor, 0.01}, 0);
+    vektor_shapebuffer_add_shape(stateOut->shapeBuffer, shp);
+
     stateOut->canvas = malloc(sizeof(VektorCanvas));
     stateOut->widgetState = wstate;
     stateOut->currentColor = vektor_color_solid(0, 0, 0);

src/core/primitives.c

@@ -59,6 +59,21 @@ void vektor_polygon_free(VektorPolygon* pg) {
     free(pg);
 }
 
+VektorCircle* vektor_circle_new(void) {
+    VektorCircle* circ = malloc(sizeof(VektorCircle));
+    circ->center = (V2){0, 0};
+    circ->radius = 0;
+    return circ;
+}
+
+void vektor_circle_set_center(VektorCircle* circle, V2 point) {
+    circle->center = point;
+}
+
+void vektor_circle_set_radius(VektorCircle* circle, double radius) {
+    circle->radius = radius;
+}
+
 VektorRectangle* vektor_rectangle_new(void) {
     VektorRectangle* rct = malloc(sizeof(VektorRectangle));
     rct->start = (V2){.x = 0, .y = 0};

src/core/primitives.h

@@ -53,6 +53,10 @@ VektorPolygon* vektor_polygon_new(void);
 void vektor_polygon_add_point(VektorPolygon* pl, V2 point);
 void vektor_polygon_free(VektorPolygon* pl);
 
+VektorCircle* vektor_circle_new(void);
+void vektor_circle_set_center(VektorCircle* circle, V2 point);
+void vektor_circle_set_radius(VektorCircle* circle, double radius);
+
 VektorRectangle* vektor_rectangle_new(void);
 void vektor_rectangle_set_end(VektorRectangle* rct, V2 point);
 void vektor_rectangle_set_start(VektorRectangle* rct, V2 point);
@@ -77,6 +81,7 @@ typedef struct {
 
 VektorBBox vektor_polyline_get_bbox(VektorPrimitive prim);
 VektorBBox vektor_polygon_get_bbox(VektorPrimitive prim);
+VektorBBox vektor_circle_get_bbox(VektorPrimitive prim);
 VektorBBox vektor_rectangle_get_bbox(VektorPrimitive prim);
 
 VektorBBox vektor_primitive_get_bbox(VektorPrimitive prim);

src/core/raster.c

@@ -3,8 +3,11 @@
 #include "primitives.h"
 #include "src/core/vector.h"
 #include "stddef.h"
+#include <math.h>
 #include <stddef.h>
 
+#define PI 3.14159265358979323846
+
 void vektor_edgebuffer_add_edge(EdgeBuffer* buffer, Edge edge) {
     if (buffer->count >= buffer->capacity) {
         buffer->capacity = buffer->capacity ? buffer->capacity * 2 : 4;
@@ -14,7 +17,7 @@ void vektor_edgebuffer_add_edge(EdgeBuffer* buffer, Edge edge) {
 }
 
 void vektor_polyline_tessellate(EdgeBuffer* buffer, VektorPolyline* line,
-                                size_t j) {
+                                size_t j, double scale) {
     for (size_t i = 0; i + 1 < line->count; i++) {
         vektor_edgebuffer_add_edge(
             buffer, (Edge){line->points[i], line->points[i + 1], 0, j});
@@ -22,7 +25,7 @@ void vektor_polyline_tessellate(EdgeBuffer* buffer, VektorPolyline* line,
 }
 
 void vektor_polygon_tessellate(EdgeBuffer* buffer, VektorPolygon* polygon,
-                               size_t j) {
+                               size_t j, double scale) {
     for (size_t i = 0; i + 1 < polygon->count; i++) {
         vektor_edgebuffer_add_edge(
             buffer, (Edge){polygon->points[i], polygon->points[i + 1], 0, j});
@@ -32,8 +35,23 @@ void vektor_polygon_tessellate(EdgeBuffer* buffer, VektorPolygon* polygon,
         (Edge){polygon->points[polygon->count - 1], polygon->points[0], 0, j});
 }
 
+void vektor_circle_tessellate(EdgeBuffer* buffer, VektorCircle* circle,
+                              size_t j, double scale) {
+    double err = 0.000025;
+    size_t res = PI * sqrt((scale * circle->radius) / (2 * err));
+    for (size_t i = 0; i < res; i++) {
+        double theta1 = (2 * PI * i) / res;
+        double theta2 = (2 * PI * (i + 1)) / res;
+        V2 p1 = (V2){circle->center.x + circle->radius * cos(theta1),
+                     circle->center.y + circle->radius * sin(theta1)};
+        V2 p2 = (V2){circle->center.x + circle->radius * cos(theta2),
+                     circle->center.y + circle->radius * sin(theta2)};
+        vektor_edgebuffer_add_edge(buffer, (Edge){p1, p2, 0, j});
+    }
+}
+
 void vektor_rectangle_tessellate(EdgeBuffer* buffer, VektorRectangle* rct,
-                                 size_t j) {
+                                 size_t j, double scale) {
     if (vec2_equals(rct->end, rct->start)) {
         return;
     }
@@ -49,22 +67,27 @@ void vektor_rectangle_tessellate(EdgeBuffer* buffer, VektorRectangle* rct,
     vektor_edgebuffer_add_edge(buffer, left);
 }
 
-void vektor_rasterize(VertexBuffer* vb, VektorShapeBuffer* shapes) {
+void vektor_rasterize(VertexBuffer* vb, VektorShapeBuffer* shapes,
+                      double scale) {
     EdgeBuffer edges = {0};
     for (size_t i = 0; i < shapes->count; i++) {
         VektorPrimitive* p = &shapes->shapes[i].primitive;
 
         switch (p->kind) {
         case VEKTOR_POLYLINE:
-            vektor_polyline_tessellate(&edges, p->polyline, i);
+            vektor_polyline_tessellate(&edges, p->polyline, i, scale);
             break;
 
         case VEKTOR_POLYGON:
-            vektor_polygon_tessellate(&edges, p->polygon, i);
+            vektor_polygon_tessellate(&edges, p->polygon, i, scale);
+            break;
+
+        case VEKTOR_CIRCLE:
+            vektor_circle_tessellate(&edges, &p->circle, i, scale);
             break;
 
         case VEKTOR_RECTANGLE:
-            vektor_rectangle_tessellate(&edges, &p->rectangle, i);
+            vektor_rectangle_tessellate(&edges, &p->rectangle, i, scale);
             break;
 
         default:

src/core/raster.h

@@ -24,11 +24,13 @@ typedef struct {
 void vektor_edgebuffer_add_edge(EdgeBuffer* edges, Edge edge);
 
 void vektor_polyline_tessellate(EdgeBuffer* edges, VektorPolyline* line,
-                                size_t i);
+                                size_t i, double scale);
 void vektor_polygon_tessellate(EdgeBuffer* buffer, VektorPolygon* polygon,
-                               size_t i);
+                               size_t i, double scale);
+void vektor_circle_tessellate(EdgeBuffer* buffer, VektorCircle* circle,
+                              size_t i, double scale);
 void vektor_rectangle_tessellate(EdgeBuffer* buffer, VektorRectangle* rct,
-                                 size_t i);
+                                 size_t i, double scale);
 
 typedef struct {
     V2 coords;
@@ -49,6 +51,7 @@ void vektor_edge_to_triangles(VertexBuffer* vb, Edge e,
                               VektorShapeBuffer* shape_buffer);
 void vektor_edges_to_triangles(VertexBuffer* vb, EdgeBuffer* edges,
                                VektorShapeBuffer* shape_buffer);
-void vektor_rasterize(VertexBuffer* vb, VektorShapeBuffer* shapes);
+void vektor_rasterize(VertexBuffer* vb, VektorShapeBuffer* shapes,
+                      double scale);
 
 #endif // RASTER_H_

src/ui/vektorcanvas.c

@@ -138,7 +138,7 @@ static gboolean render(GtkGLArea* a, GdkGLContext* ctx,
                        VektorCanvasRenderInfo* renderInfo) {
     vb.count = 0;
 
-    vektor_rasterize(&vb, renderInfo->shapes);
+    vektor_rasterize(&vb, renderInfo->shapes, 2);
     size_t shape_vertex_count =
         vb.count; // remember how many vertices belong to shapes