lovr.graphics.plane;

src/graphics/graphics.c

@@ -305,6 +305,50 @@ void lovrGraphicsLine(float* points, int count) {
   lovrGraphicsDrawShape(GL_LINE_STRIP);
 }
 
+void lovrGraphicsPlane(DrawMode mode, float x, float y, float z, float size, float nx, float ny, float nz) {
+  float points[] = {
+    -.5, .5, 0,
+    .5, .5, 0,
+    .5, -.5, 0,
+    -.5, -.5, 0
+  };
+
+  // Normalize the normal vector
+  float len = sqrt(nx * nx + ny * ny + nz + nz);
+  if (len != 1) {
+    len = 1 / len;
+    nx *= len;
+    ny *= len;
+    nz *= len;
+  }
+
+  // Vector perpendicular to the normal vector and the vector of the default geometry (cross product)
+  float cx = -ny;
+  float cy = nx;
+  float cz = 0.f;
+
+  // Angle between normal vector and the normal vector of the default geometry (dot product)
+  float theta = acos(nz);
+
+  float transform[16];
+  mat4_setTranslation(transform, x, y, z);
+  mat4_scale(transform, size, size, size);
+  mat4_rotate(transform, theta, cx, cy, cz);
+  lovrGraphicsPush();
+  lovrGraphicsTransform(transform);
+
+  if (mode == DRAW_MODE_LINE) {
+    lovrGraphicsSetShapeData(points, 12, NULL, 0);
+    lovrGraphicsDrawShape(GL_LINE_LOOP);
+  } else if (mode == DRAW_MODE_FILL) {
+    unsigned int indices[] = { 0, 3, 1, 2 };
+    lovrGraphicsSetShapeData(points, 12, indices, 4);
+    lovrGraphicsDrawShape(GL_TRIANGLE_STRIP);
+  }
+
+  lovrGraphicsPop();
+}
+
 void lovrGraphicsCube(DrawMode mode, float x, float y, float z, float size, float angle, float axisX, float axisY, float axisZ) {
   float points[] = {
     // Front

src/graphics/graphics.h

@@ -89,6 +89,7 @@ void lovrGraphicsGetDimensions(int* width, int* height);
 void lovrGraphicsSetShapeData(float* data, int count, unsigned int* indices, int indexCount);
 void lovrGraphicsDrawShape();
 void lovrGraphicsLine(float* points, int count);
+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);
 Buffer* lovrGraphicsNewBuffer(int size, BufferDrawMode drawMode, BufferUsage usage);
 Model* lovrGraphicsNewModel(const char* path);

src/lovr/graphics.c

@@ -33,6 +33,7 @@ const luaL_Reg lovrGraphics[] = {
   { "rotate", l_lovrGraphicsRotate },
   { "scale", l_lovrGraphicsScale },
   { "line", l_lovrGraphicsLine },
+  { "plane", l_lovrGraphicsPlane },
   { "cube", l_lovrGraphicsCube },
   { "getWidth", l_lovrGraphicsGetWidth },
   { "getHeight", l_lovrGraphicsGetHeight },
@@ -342,6 +343,24 @@ int l_lovrGraphicsLine(lua_State* L) {
   return 0;
 }
 
+int l_lovrGraphicsPlane(lua_State* L) {
+  const char* userDrawMode = luaL_checkstring(L, 1);
+  DrawMode* drawMode = (DrawMode*) map_get(&DrawModes, userDrawMode);
+  if (!drawMode) {
+    return luaL_error(L, "Invalid draw mode: '%s'", userDrawMode);
+  }
+
+  float x = luaL_optnumber(L, 2, 0.f);
+  float y = luaL_optnumber(L, 3, 0.f);
+  float z = luaL_optnumber(L, 4, 0.f);
+  float s = luaL_optnumber(L, 5, 1.f);
+  float nx = luaL_optnumber(L, 6, 0.f);
+  float ny = luaL_optnumber(L, 7, 1.f);
+  float nz = luaL_optnumber(L, 8, 0.f);
+  lovrGraphicsPlane(*drawMode, x, y, z, s, nx, ny, nz);
+  return 0;
+}
+
 int l_lovrGraphicsCube(lua_State* L) {
   const char* userDrawMode = luaL_checkstring(L, 1);
   DrawMode* drawMode = (DrawMode*) map_get(&DrawModes, userDrawMode);

src/lovr/graphics.h

@@ -37,6 +37,7 @@ int l_lovrGraphicsTranslate(lua_State* L);
 int l_lovrGraphicsRotate(lua_State* L);
 int l_lovrGraphicsScale(lua_State* L);
 int l_lovrGraphicsLine(lua_State* L);
+int l_lovrGraphicsPlane(lua_State* L);
 int l_lovrGraphicsCube(lua_State* L);
 int l_lovrGraphicsGetWidth(lua_State* L);
 int l_lovrGraphicsGetHeight(lua_State* L);