lovr.graphics.arc;

src/api/graphics.c

@@ -12,6 +12,7 @@
 #include <math.h>
 #include <stdbool.h>
 
+map_int_t ArcModes;
 map_int_t BlendAlphaModes;
 map_int_t BlendModes;
 map_int_t CompareModes;
@@ -82,6 +83,11 @@ int l_lovrGraphicsInit(lua_State* L) {
   luax_registertype(L, "Shader", lovrShader);
   luax_registertype(L, "Texture", lovrTexture);
 
+  map_init(&ArcModes);
+  map_set(&ArcModes, "pie", ARC_MODE_PIE);
+  map_set(&ArcModes, "open", ARC_MODE_OPEN);
+  map_set(&ArcModes, "closed", ARC_MODE_CLOSED);
+
   map_init(&BlendAlphaModes);
   map_set(&BlendAlphaModes, "alphamultiply", BLEND_ALPHA_MULTIPLY);
   map_set(&BlendAlphaModes, "premultiplied", BLEND_PREMULTIPLIED);
@@ -525,6 +531,22 @@ int l_lovrGraphicsBox(lua_State* L) {
   return luax_rectangularprism(L, false);
 }
 
+int l_lovrGraphicsArc(lua_State* L) {
+  DrawMode drawMode = *(DrawMode*) luax_checkenum(L, 1, &DrawModes, "draw mode");
+  ArcMode arcMode = ARC_MODE_PIE;
+  int index = 2;
+  if (lua_type(L, 2) == LUA_TSTRING) {
+    arcMode = *(ArcMode*) luax_checkenum(L, index++, &ArcModes, "arc mode");
+  }
+  float transform[16];
+  index = luax_readtransform(L, index, transform, true);
+  float theta1 = luaL_optnumber(L, index++, 0);
+  float theta2 = luaL_optnumber(L, index++, 2 * M_PI);
+  int segments = luaL_optinteger(L, index, 32) * fabsf(theta2 - theta1) * 2 * M_PI + .5f;
+  lovrGraphicsArc(drawMode, arcMode, transform, theta1, theta2, segments);
+  return 0;
+}
+
 int l_lovrGraphicsCircle(lua_State* L) {
   DrawMode drawMode = *(DrawMode*) luax_checkenum(L, 1, &DrawModes, "draw mode");
   float transform[16];
@@ -824,6 +846,7 @@ const luaL_Reg lovrGraphics[] = {
   { "plane", l_lovrGraphicsPlane },
   { "cube", l_lovrGraphicsCube },
   { "box", l_lovrGraphicsBox },
+  { "arc", l_lovrGraphicsArc },
   { "circle", l_lovrGraphicsCircle },
   { "cylinder", l_lovrGraphicsCylinder },
   { "sphere", l_lovrGraphicsSphere },

src/graphics/graphics.c

@@ -707,38 +707,49 @@ void lovrGraphicsBox(DrawMode mode, mat4 transform) {
   lovrGraphicsPop();
 }
 
-void lovrGraphicsCircle(DrawMode mode, mat4 transform, int segments) {
+void lovrGraphicsArc(DrawMode mode, ArcMode arcMode, mat4 transform, float theta1, float theta2, int segments) {
+  if (fabsf(theta1 - theta2) >= 2 * M_PI) {
+    theta1 = 0;
+    theta2 = 2 * M_PI;
+  }
+
   lovrGraphicsPush();
   lovrGraphicsMatrixTransform(MATRIX_MODEL, transform);
 
   vec_clear(&state.streamData);
 
+  if (arcMode == ARC_MODE_PIE && fabsf(theta1 - theta2) < 2 * M_PI) {
+    vec_push(&state.streamData, 0);
+    vec_push(&state.streamData, 0);
+    vec_push(&state.streamData, 0);
+
+    if (mode == DRAW_MODE_FILL) {
+      vec_push(&state.streamData, 0);
+      vec_push(&state.streamData, 0);
+      vec_push(&state.streamData, 1);
+
+      vec_push(&state.streamData, .5);
+      vec_push(&state.streamData, .5);
+    }
+  }
+
+  float theta = theta1;
+  float angleShift = (theta2 - theta1) / (float) segments;
+
   if (mode == DRAW_MODE_LINE) {
-    for (int i = 0; i < segments; i++) {
-      float theta = i / (float) segments * 2 * M_PI;
+    for (int i = 0; i <= segments; i++) {
       float x = cos(theta) * .5;
       float y = sin(theta) * .5;
       vec_push(&state.streamData, x);
       vec_push(&state.streamData, y);
       vec_push(&state.streamData, 0);
+      theta += angleShift;
     }
 
     lovrGraphicsSetDefaultShader(SHADER_DEFAULT);
-    lovrGraphicsDrawPrimitive(GL_LINE_LOOP, false, false, false);
+    lovrGraphicsDrawPrimitive(arcMode == ARC_MODE_OPEN ? GL_LINE_STRIP : GL_LINE_LOOP, false, false, false);
   } else if (mode == DRAW_MODE_FILL) {
-    vec_push(&state.streamData, 0);
-    vec_push(&state.streamData, 0);
-    vec_push(&state.streamData, 0);
-
-    vec_push(&state.streamData, 0);
-    vec_push(&state.streamData, 0);
-    vec_push(&state.streamData, 1);
-
-    vec_push(&state.streamData, .5);
-    vec_push(&state.streamData, .5);
-
     for (int i = 0; i <= segments; i++) {
-      float theta = i / (float) segments * 2 * M_PI;
       float x = cos(theta) * .5;
       float y = sin(theta) * .5;
       vec_push(&state.streamData, x);
@@ -751,6 +762,7 @@ void lovrGraphicsCircle(DrawMode mode, mat4 transform, int segments) {
 
       vec_push(&state.streamData, x + .5);
       vec_push(&state.streamData, 1 - (y + .5));
+      theta += angleShift;
     }
 
     lovrGraphicsSetDefaultShader(SHADER_DEFAULT);
@@ -760,6 +772,10 @@ void lovrGraphicsCircle(DrawMode mode, mat4 transform, int segments) {
   lovrGraphicsPop();
 }
 
+void lovrGraphicsCircle(DrawMode mode, mat4 transform, int segments) {
+  lovrGraphicsArc(mode, ARC_MODE_OPEN, transform, 0, 2 * M_PI, segments);
+}
+
 void lovrGraphicsCylinder(float x1, float y1, float z1, float x2, float y2, float z2, float r1, float r2, bool capped, int segments) {
   float axis[3] = { x1 - x2, y1 - y2, z1 - z2 };
   float n[3] = { x1 - x2, y1 - y2, z1 - z2 };

src/graphics/graphics.h

@@ -35,6 +35,12 @@ typedef enum {
   DRAW_MODE_LINE
 } DrawMode;
 
+typedef enum {
+  ARC_MODE_PIE,
+  ARC_MODE_OPEN,
+  ARC_MODE_CLOSED
+} ArcMode;
+
 typedef enum {
   WINDING_CLOCKWISE = GL_CW,
   WINDING_COUNTERCLOCKWISE = GL_CCW
@@ -163,6 +169,7 @@ void lovrGraphicsTriangle(DrawMode mode, float* points);
 void lovrGraphicsPlane(DrawMode mode, mat4 transform);
 void lovrGraphicsPlaneFullscreen(Texture* texture);
 void lovrGraphicsBox(DrawMode mode, mat4 transform);
+void lovrGraphicsArc(DrawMode mode, ArcMode, mat4 transform, float theta1, float theta2, int segments);
 void lovrGraphicsCircle(DrawMode mode, mat4 transform, int segments);
 void lovrGraphicsCylinder(float x1, float y1, float z1, float x2, float y2, float z2, float r1, float r2, bool capped, int segments);
 void lovrGraphicsSphere(mat4 transform, int segments);