Add support for rotated gradients

source/lithium/drawlist.cpp

@@ -45,6 +45,12 @@ PD_API void Drawlist::PathFill(const PD::Color& color) {
   PathClear();
 }
 
+PD_API void Drawlist::PathFillGradient(const PD::Color& a, const PD::Color& b,
+                                       float rad) {
+  DrawConvexPolyFilled(pPath, a, b, rad);
+  PathClear();
+}
+
 PD_API void Drawlist::PathArcToN(const fvec2& c, float r, float amin,
                                  float amax, int s) {
   // Path.push_back(c);
@@ -229,9 +235,9 @@ PD_API void Drawlist::DrawPolyLine(const Pool<fvec2>& points,
   }
   UnbindTexture();
   auto& cmd = NewCommand();
-  bool close = (flags & (1 << 0));
+  bool close = (flags & LiDrawFlags_Close);
   int num_points = close ? (int)points.size() : (int)points.size() - 1;
-  if (flags & (1 << 1)) {
+  if (flags & LiDrawFlags_AA) {
     // TODO: Find a way to draw less garbage looking lines
   } else {
     // Non antialiased lines look awful when rendering with thickness != 1
@@ -282,6 +288,57 @@ PD_API void Drawlist::DrawConvexPolyFilled(const Pool<fvec2>& points,
   }
 }
 
+PD_API void Drawlist::DrawConvexPolyFilled(const Pool<fvec2>& points,
+                                           const PD::Color& a,
+                                           const PD::Color b, float rad) {
+  if (points.size() < 3) {
+    return;  // Need at least three points
+  }
+
+  fvec2 dir = fvec2(std::cos(rad), std::sin(rad));
+  // Support for Custom Textures (UV calculation)
+  float minX = points[0].x, minY = points[0].y;
+  float maxX = minX, maxY = minY;
+  // Check for the max and min Positions
+  for (const auto& it : points) {
+    if (it.x < minX) minX = it.x;
+    if (it.y < minY) minY = it.y;
+    if (it.x > maxX) maxX = it.x;
+    if (it.y > maxY) maxY = it.y;
+  }
+  // Get Short defines for UV
+  // (Bottom Right is not required)
+  auto uv_tl = pCurrentTexture.GetUV().TopLeft();
+  auto uv_tr = pCurrentTexture.GetUV().TopRight();
+  auto uv_bl = pCurrentTexture.GetUV().BotLeft();
+
+  // Gradient
+  float tmin = std::numeric_limits<float>::max();
+  float tmax = std::numeric_limits<float>::lowest();
+  for (const auto& p : points) {
+    float t = p.x * dir.x + p.y * dir.y;
+    if (t < tmin) tmin = t;
+    if (t > tmax) tmax = t;
+  }
+  // potential div0
+  float irange = (tmax != tmin) ? (1.0f / (tmax - tmin)) : 0.0f;
+  // Command building (oder so)
+  auto& cmd = NewCommand();
+  cmd.Reserve(points.size(), (points.size() - 2) * 3);
+  // Render
+  for (int i = 2; i < (int)points.size(); i++) {
+    cmd.Add(0, i, i - 1);
+  }
+  // Why was this for loop not used in normal Convex Poly filled???
+  for (auto& it : points) {
+    // Calculate U and V coords
+    float u = uv_tl.x + ((it.x - minX) / (maxX - minX)) * (uv_tr.x - uv_tl.x);
+    float v = uv_tl.y + ((it.y - minY) / (maxY - minY)) * (uv_bl.y - uv_tl.y);
+    float t = it.x * dir.x + it.y * dir.y;
+    cmd.Add(Vertex(it, fvec2(u, v), PD::Color(a).Lerp(b, (t - tmin) * irange)));
+  }
+}
+
 PD_API void Drawlist::PrimQuad(Command& cmd, const Rect& quad, const Rect& uv,
                                const PD::Color& color) {
   cmd.Reserve(4, 6);