fix equirectangular shader for higher precision, add polygon draw mode

engine/shape.h

@@ -9,9 +9,11 @@ protected:
     GLuint arrays[2]{ 0 };
     GLuint count[2]{ 0 };
     GLvoid* ioff[2]{ 0 };
-    struct vertex_t { glm::vec4 pos; glm::vec2 uvs; };
+    bool use_idx = true;
 public:
+    struct vertex_t { glm::vec4 pos; glm::vec2 uvs; };
     bool create_buffers(GLvoid* idx, GLvoid* vertices, int isize, int vsize);
+    bool create_buffers(GLvoid* vertices, int vsize);
     void draw_fill() const;
     void draw_stroke() const;
     virtual bool create_attrib() { return true; };
@@ -49,18 +51,35 @@ protected:
 
 class LineSegment : public Shape
 {
-    void create_impl(GLushort* idx, vertex_t* vertices);
 public:
     bool create()
     {
-        static GLushort idx[2];
         static vertex_t vertices[2];
-        create_impl(idx, vertices);
-        return create_buffers(idx, vertices, sizeof(idx), sizeof(vertices));
+        count[0] = 2;
+        count[1] = 2;
+        ioff[0] = (GLvoid*)0;
+        ioff[1] = (GLvoid*)0;
+        vertices[0] = { { 0, 0, 0, 1 },{ 0, 0 } }; // A
+        vertices[1] = { { 0, 0, 0, 1 },{ 0, 1 } }; // B
+        return create_buffers(vertices, sizeof(vertices));
     }
     void update_vertices(const glm::vec4 data[2]);
 };
 
+class DynamicShape : public Shape
+{
+public:
+    bool create(vertex_t* vertices = nullptr, int vcount = 0)
+    {
+        count[0] = vcount;
+        count[1] = vcount;
+        ioff[0] = (GLvoid*)0;
+        ioff[1] = (GLvoid*)0;
+        return create_buffers(vertices, sizeof(vertex_t) * vcount);
+    }
+    void update_vertices(vertex_t* vertices, int vcount);
+};
+
 class Plane : public Shape
 {
     void create_impl(float w, float h, int div, GLushort* idx, vertex_t* vertices);