add universe rotation

assets/shader/starfield.vs

@@ -8,9 +8,10 @@ out float _size_;
 out vec3 _color_;
 
 uniform mat4 view;
+uniform mat4 model;
 
 void main() {
-	vec4 position = view * vec4(_position, 1.f);
+	vec4 position = view * model * vec4(_position, 1.f);
 	gl_Position = position;
 	_size_ = _size;
 	_color_ = _color;

include/rendering/rendering_system.hpp

@@ -153,7 +153,7 @@ namespace gdw {
 		void render_navMesh(camera_component &camera);
 		void render_final_image();
 		void generate_starfield();
-		void render_starfield(camera_component& camera);
+		void render_starfield(float delta_time, camera_component& camera);
 
 
 		void register_component(camera_component* component);

src/rendering/rendering_system.cpp

@@ -330,7 +330,7 @@ namespace gdw {
 
 		render_gbuffer(delta_time, *camera);
 		render_lights(*camera);
-		render_starfield(*camera);
+		render_starfield(delta_time, *camera);
 		render_non_opauqe_geometry(delta_time, *camera);
 		render_final_image();
 		if(engine_.getConfig().get("navDebug",true))
@@ -830,7 +830,18 @@ namespace gdw {
 		starfield_size_ = stars.size();
 	}
 
-	void rendering_system::render_starfield(camera_component& camera) {
+	void rendering_system::render_starfield(float delta_time, camera_component& camera) {
+		static auto alpha = 0.f;
+		static const auto planet_acceleration_ = 0.005f;
+		static const auto planet_center = glm::vec3(80.f, -20.f, -100.f);
+		alpha += planet_acceleration_ *  delta_time;
+		if (alpha >= 2.f * glm::pi<float>()) {
+			alpha = 0.f;
+		}
+		auto model = glm::translate(glm::mat4(1.f), planet_center);
+		model *= glm::toMat4(glm::angleAxis(alpha, glm::vec3(0.f, 1.f, 0.f)));
+		model *= glm::translate(glm::mat4(1.f), -planet_center);
+
 		glEnable(GL_DEPTH_TEST);
 		glDepthMask(GL_FALSE);
 		glEnable(GL_BLEND);
@@ -839,6 +850,7 @@ namespace gdw {
 		starfield_program_.use();
 		starfield_program_.uniform("projection", false, camera.projection());
 		starfield_program_.uniform("view", false, camera.view());
+		starfield_program_.uniform("model", false, model);
 		starfield_program_.uniform("albedo_texture", 0);
 		star_texture_->bind(0);
 		glDrawArraysInstanced(GL_POINTS, 0, 1, starfield_size_);