lovr.graphics.triangle;

src/graphics/graphics.c

@@ -355,6 +355,28 @@ void lovrGraphicsLine(float* points, int count) {
   lovrGraphicsDrawLinedShape(GL_LINE_STRIP);
 }
 
+void lovrGraphicsTriangle(DrawMode mode, float* points) {
+  if (mode == DRAW_MODE_LINE) {
+    lovrGraphicsSetShapeData(points, 9, NULL, 0);
+    lovrGraphicsDrawLinedShape(GL_LINE_LOOP);
+  } else {
+    float n[3] = {
+      points[1] * points[5] - points[2] * points[4],
+      points[2] * points[3] - points[0] * points[5],
+      points[0] * points[4] - points[1] * points[3]
+    };
+
+    float data[18] = {
+      points[0], points[1], points[2], n[0], n[1], n[2],
+      points[3], points[4], points[5], n[0], n[1], n[2],
+      points[6], points[7], points[8], n[0], n[1], n[2]
+    };
+
+    lovrGraphicsSetShapeData(data, 18, NULL, 0);
+    lovrGraphicsDrawFilledShape();
+  }
+}
+
 void lovrGraphicsPlane(DrawMode mode, float x, float y, float z, float size, float nx, float ny, float nz) {
 
   // Normalize the normal vector

src/graphics/graphics.h

@@ -89,6 +89,7 @@ void lovrGraphicsDrawLinedShape(GLenum mode);
 void lovrGraphicsDrawFilledShape();
 void lovrGraphicsPoints(float* points, int count);
 void lovrGraphicsLine(float* points, int count);
+void lovrGraphicsTriangle(DrawMode mode, float* points);
 void lovrGraphicsPlane(DrawMode mode, float x, float y, float z, float size, float nx, float ny, float nz);
 void lovrGraphicsCube(DrawMode mode, float x, float y, float z, float size, float angle, float axisX, float axisY, float axisZ);
 void lovrGraphicsSkybox(Skybox* skybox, float angle, float ax, float ay, float az);

src/lovr/graphics.c

@@ -17,7 +17,7 @@ static void luax_readvertices(lua_State* L, int index, vec_float_t* points) {
     return;
   }
 
-  int count = isTable ? lua_objlen(L, index) : lua_gettop(L);
+  int count = isTable ? lua_objlen(L, index) : lua_gettop(L) - index + 1;
   if (count % 3 != 0) {
     vec_deinit(points);
     luaL_error(L, "Number of coordinates must be a multiple of 3, got '%d'", count);
@@ -70,6 +70,7 @@ const luaL_Reg lovrGraphics[] = {
   { "scale", l_lovrGraphicsScale },
   { "points", l_lovrGraphicsPoints },
   { "line", l_lovrGraphicsLine },
+  { "triangle", l_lovrGraphicsTriangle },
   { "plane", l_lovrGraphicsPlane },
   { "cube", l_lovrGraphicsCube },
   { "getWidth", l_lovrGraphicsGetWidth },
@@ -384,6 +385,20 @@ int l_lovrGraphicsLine(lua_State* L) {
   return 0;
 }
 
+int l_lovrGraphicsTriangle(lua_State* L) {
+  DrawMode* drawMode = (DrawMode*) luax_checkenum(L, 1, &DrawModes, "draw mode");
+  int top = lua_gettop(L);
+  if (top != 10) {
+    return luaL_error(L, "Expected 9 coordinates to make a triangle, got %d values", top - 1);
+  }
+  vec_float_t points;
+  vec_init(&points);
+  luax_readvertices(L, 2, &points);
+  lovrGraphicsTriangle(*drawMode, points.data);
+  vec_deinit(&points);
+  return 0;
+}
+
 int l_lovrGraphicsPlane(lua_State* L) {
   const char* userDrawMode = luaL_checkstring(L, 1);
   DrawMode* drawMode = (DrawMode*) map_get(&DrawModes, userDrawMode);

src/lovr/graphics.h

@@ -43,6 +43,7 @@ int l_lovrGraphicsRotate(lua_State* L);
 int l_lovrGraphicsScale(lua_State* L);
 int l_lovrGraphicsPoints(lua_State* L);
 int l_lovrGraphicsLine(lua_State* L);
+int l_lovrGraphicsTriangle(lua_State* L);
 int l_lovrGraphicsPlane(lua_State* L);
 int l_lovrGraphicsCube(lua_State* L);
 int l_lovrGraphicsGetWidth(lua_State* L);