start work on efficient curve renderer

CMakeLists.txt

@@ -51,7 +51,7 @@ macro(blt_add_project name source type)
     project(tower-defense)
 endmacro()
 
-project(tower-defense VERSION 0.0.16)
+project(tower-defense VERSION 0.0.17)
 
 option(ENABLE_ADDRSAN "Enable the address sanitizer" OFF)
 option(ENABLE_UBSAN "Enable the ub sanitizer" OFF)

include/map.h

@@ -20,20 +20,48 @@
 #define MAP_H
 
 #include <blt/math/vectors.h>
+#include <blt/gfx/renderer/batch_2d_renderer.h>
 #include <fwddecl.h>
 #include <enemies.h>
 
 namespace td
 {
 
+	struct curve_mesh_data_t
+	{
+		struct line_vertex_t
+		{
+			blt::vec3 pos;
+			blt::vec2 uv;
+		};
+
+		[[nodiscard]] std::unique_ptr<blt::gfx::vertex_array_t> to_vertex_array() const;
+		void populate_vertex_array(blt::gfx::vertex_array_t& va) const;
+
+		[[nodiscard]] std::vector<line_vertex_t> calculate_vertices() const;
+
+		curve_mesh_data_t& with(const curve_mesh_data_t& mesh)
+		{
+			lines.insert(lines.end(), mesh.lines.begin(), mesh.lines.end());
+			return *this;
+		}
+
+		std::vector<blt::gfx::line2d_t> lines;
+	};
+
 	class curve_t
 	{
 	public:
 		curve_t(blt::vec2 p0, blt::vec2 p1, blt::vec2 p2);
+		curve_t(blt::vec2 p0, blt::vec2 p1, blt::vec2 p2, blt::vec2 p3);
 
 		[[nodiscard]] blt::vec2 get_point(float t) const;
+
+		[[nodiscard]] std::vector<blt::gfx::line2d_t> to_lines(blt::i32 segments) const;
+
+		[[nodiscard]] curve_mesh_data_t to_mesh(blt::i32 segments) const;
 	private:
-		blt::vec2 m_p0, m_p1, m_p2;
+		blt::vec2 m_p0, m_p1, m_p2, m_p3;
 	};
 
 	class path_segment_t

src/main.cpp

@@ -13,7 +13,7 @@ blt::gfx::first_person_camera camera;
 float t = 0;
 float dir = 1;
 
-td::curve_t curve{blt::vec2{250, 250}, blt::vec2{500, 500}, blt::vec2{750, 250}};
+td::curve_t curve{blt::vec2{250, 250}, blt::vec2{400, 500}, blt::vec2{600, 500}, blt::vec2{750, 250}};
 
 void init(const blt::gfx::window_data&)
 {
@@ -51,6 +51,9 @@ void update(const blt::gfx::window_data& data)
 
     auto pos = curve.get_point(t);
     renderer_2d.drawRectangleInternal(blt::make_color(1, 0, 0), blt::gfx::rectangle2d_t{pos, blt::vec2{25, 25}});
+    auto lines = curve.to_lines(32);
+    for (const auto& line : lines)
+        renderer_2d.drawLineInternal(blt::make_color(0, 1,0), line);
 
     renderer_2d.render(data.width, data.height);
 }

src/map.cpp

@@ -19,14 +19,57 @@
 
 namespace td
 {
-	curve_t::curve_t(const blt::vec2 p0, const blt::vec2 p1, const blt::vec2 p2): m_p0(p0), m_p1(p1), m_p2(p2)
+	curve_t::curve_t(const blt::vec2 p0, const blt::vec2 p1, const blt::vec2 p2): m_p0(p0), m_p1(p1), m_p2(p1), m_p3(p2)
+	{}
+
+	curve_t::curve_t(const blt::vec2 p0, const blt::vec2 p1, const blt::vec2 p2, const blt::vec2 p3): m_p0(p0), m_p1(p1), m_p2(p2), m_p3(p3)
 	{}
 
 	blt::vec2 curve_t::get_point(const float t) const
 	{
 		const auto t_inv = 1.0f - t;
 		const auto t_inv_sq = t_inv * t_inv;
+		const auto t_inv_cub = t_inv_sq * t_inv;
 		const auto t_sq = t * t;
-		return t_inv_sq * m_p0 + 2.0f * t_inv * t * m_p1 + t_sq * m_p2;
+		const auto t_cub = t_sq * t;
+		return t_inv_cub * m_p0 + 3 * t_inv_sq * t * m_p1 + 3 * t_inv * t_sq * m_p2 + t_cub * m_p3;
+	}
+
+	std::vector<blt::gfx::line2d_t> curve_t::to_lines(const blt::i32 segments) const
+	{
+		std::vector<blt::gfx::line2d_t> lines;
+		float t = 0;
+		const float diff = 1.0f / static_cast<float>(segments);
+
+		for (blt::i32 i = 0; i < segments; ++i)
+		{
+			auto begin = get_point(t);
+			t += diff;
+			auto end = get_point(t);
+
+			lines.emplace_back(begin, end);
+		}
+
+		return lines;
+	}
+
+	std::unique_ptr<blt::gfx::vertex_array_t> curve_mesh_data_t::to_vertex_array() const
+	{}
+
+	void curve_mesh_data_t::populate_vertex_array(blt::gfx::vertex_array_t& va) const
+	{}
+
+	std::vector<curve_mesh_data_t::line_vertex_t> curve_mesh_data_t::calculate_vertices() const
+	{
+		std::vector<line_vertex_t> vertices;
+
+		return vertices;
+	}
+
+	curve_mesh_data_t curve_t::to_mesh(const blt::i32 segments) const
+	{
+		curve_mesh_data_t mesh_data;
+		mesh_data.lines = to_lines(segments);
+		return mesh_data;
 	}
 }