Mouse, constraints in cloth step now

src/app.cpp

@@ -1,9 +1,11 @@
 #include "app.hpp"
 #include "cloth.hpp"
+#include "mouse.hpp"
 #include "window.hpp"
 #include "vec.hpp"
 #include <SDL2/SDL_events.h>
 #include <SDL2/SDL_keycode.h>
+#include <SDL2/SDL_mouse.h>
 #include <SDL2/SDL_render.h>
 #include <SDL2/SDL_timer.h>
 #include <SDL2/SDL_video.h>
@@ -22,6 +24,7 @@ App* app_init(App_config conf) {
     }
     app->conf = conf;
     
+    app->mouse = new_mouse(Vec2{0, 0}, 30);
     app->window = new_window(conf.win_name, conf.window_dimensions);
     app->cloth = new_cloth(
         conf.cloth_startpos,
@@ -61,12 +64,44 @@ void app_handle_input(App* app) {
                 case SDLK_SPACE:
                     toggle_pause(app);
                     break; 
-            }        
+                
+                case SDLK_LEFT:
+                    if (app->conf.timestep >= 0.25) {
+                        app->conf.timestep -= 0.25;
+                    }
+                    break;
+                
+                case SDLK_RIGHT:
+                    app->conf.timestep += 0.25;
+                    break;
+            }
+
+        case SDL_MOUSEMOTION:
+            app->mouse->last_pos = app->mouse->pos;
+            app->mouse->pos = Vec2{
+                static_cast<unsigned int>(event.motion.x),
+                static_cast<unsigned int>(event.motion.y)
+            };
+            break;        
+        
+        case SDL_MOUSEBUTTONDOWN:
+            if (event.button.button == SDL_BUTTON_LEFT) {
+                app->mouse->left_button_clicked = true;
+            }
+            break;
+
+        case SDL_MOUSEBUTTONUP:
+            if (event.button.button == SDL_BUTTON_LEFT) {
+                app->mouse->left_button_clicked = false;
+            }
+            break;
         }
+
     }
 }
 
-void app_render(App* app) {    
+void app_render(App* app) {
+    SDL_RenderClear(app->window->renderer);    
     fill_screen(app->window, app->conf.background_color);
     draw_cloth(
         app->window, app->cloth,
@@ -83,16 +118,19 @@ void app_update(App* app) {
     int updated_window_h;
     SDL_GetWindowSize(app->window->sdl_win, &updated_window_w, &updated_window_h);
     app->window->dimensions = Vec2{(unsigned int) updated_window_w, (unsigned int) updated_window_h};
+    if (app->cloth->constraint_bottom_right.x != (unsigned int) updated_window_w || app->cloth->constraint_bottom_right.y != (unsigned int) updated_window_h) {
+        app->cloth->constraint_bottom_right.x = app->window->dimensions.x;
+        app->cloth->constraint_bottom_right.y = app->window->dimensions.y-5;
+    }
 
-    app->cloth->constraint_bottom_right.x = app->window->dimensions.x;
-    app->cloth->constraint_bottom_right.y = app->window->dimensions.y-5;
-    cloth_step(app->cloth, app->conf.gravity, 1);
-    satisfy_cloth_constraints(app->cloth);
+    cloth_step(app->cloth, app->mouse, app->conf.gravity, app->conf.timestep);
 }
 
 void destroy_app(App* app) {
+    destroy_mouse(app->mouse);
     destroy_cloth(app->cloth);
     destroy_window(app->window);
+    app->mouse = NULL;
     app->cloth = NULL;
     app->window = NULL;
     app->is_running = false;

src/app.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "mouse.hpp"
 #include "window.hpp"
 #include "cloth.hpp"
 #include <SDL2/SDL_render.h>
@@ -13,6 +14,7 @@ struct App_config {
     Vec2f gravity;
     float efficiency_factor;
     float friction_factor;
+    float timestep;
     RGB background_color;
     RGB point_color;
     RGB point_selected_color;
@@ -23,6 +25,7 @@ struct App {
     bool is_running;
     bool paused;
     App_config conf;
+    Mouse* mouse;
     Window* window;
     Cloth* cloth;
 };

src/cloth.cpp

@@ -1,5 +1,7 @@
 #include "cloth.hpp"
 #include "connection.hpp"
+#include "mouse.hpp"
+#include <cmath>
 #include <cstddef>
 #include <cstdio>
 #include <vector>
@@ -26,18 +28,12 @@ Cloth* new_cloth(
     bool frozen_point = false;
     for (unsigned int y = 0; y < dimensions.y; y += spacing) {        
         for (unsigned int x = 0; x < dimensions.x; x += spacing) {
-            // if (y == 0 && x == new_cloth->dimensions.x/2) {
-            //     frozen_point = true;
-            // } else {
-            //     frozen_point = false;
-            // }
-            
             Point* new_point = new Point{
-                .x = static_cast<float>(startpos.x + x),
-                .y = static_cast<float>(startpos.y + y),
+                .pos = Vec2f{static_cast<float>(startpos.x + x), static_cast<float>(startpos.y + y)},
                 .mass = 10.0f,
                 .frozen = frozen_point,
                 .selected = false,
+                .radius = 2.5,
             };
             new_cloth->points.push_back(new_point);
 
@@ -78,58 +74,58 @@ void destroy_cloth(Cloth* cloth) {
     delete cloth;
 }
 
-// calculate forces and actually MOVE points 
-void cloth_step(Cloth* cloth, Vec2f gravity_vec, float timedelta) {
+// calculate forces, move points and satisfy constraints 
+void cloth_step(Cloth* cloth, Mouse* mouse, Vec2f gravity_vec, float timedelta) {
     for (Point* p : cloth->points) {
         if (p->frozen) {
             continue;
         }
-        
-        // calculate velocity
-        if (p->y == cloth->constraint_bottom_right.y) {
-            // if this point's x velocity is too small -> just stop it
-            // else -> handle friction
-            if (p->velocity.x <= 0.5) {
-                p->velocity.x = 0;
-            } else {
-                p->velocity.x = p->velocity.x*cloth->friction_factor * timedelta;
-            }
+
+        // handle mouse
+        // ((x0 - x1)^2 + (y0 - y1)^2)^0.5
+        float distance_to_point = std::sqrt(pow(p->pos.x - mouse->pos.x, 2.0f)+pow(p->pos.y - mouse->pos.y, 2.0f));
+        if (distance_to_point <= mouse->cursor_radius_size) {
+            p->selected = true;
         } else {
-            p->velocity.x = p->velocity.x+(gravity_vec.x/p->mass) * timedelta;
-            p->velocity.y = p->velocity.y+(gravity_vec.y/p->mass) * timedelta;
+            p->selected = false;
+        }
+
+        if (p->selected && mouse->left_button_clicked) {
+            p->pos = Vec2f{(float) mouse->pos.x, (float) mouse->pos.y};
         }
 
+        // calculate velocity
+        p->velocity.x = (p->velocity.x + (gravity_vec.x/p->mass)) * timedelta;
+        p->velocity.y = (p->velocity.y + (gravity_vec.y/p->mass)) * timedelta;
+
         // move point
-        p->x += p->velocity.x;
-        p->y += p->velocity.y;
-    }
-}
+        p->pos.x += p->velocity.x;
+        p->pos.y += p->velocity.y;
 
-// handle constraints, bounces
-void satisfy_cloth_constraints(Cloth* cloth) {
-    for (Point* p : cloth->points) {
+        // now handle constraints
         // bottom
-        if (p->y > cloth->constraint_bottom_right.y) {
-            p->y = cloth->constraint_bottom_right.y;
-            p->velocity.y = -p->velocity.y*cloth->efficiency_factor;
+        if (p->pos.y >= cloth->constraint_bottom_right.y) {
+            p->pos.y = cloth->constraint_bottom_right.y;            
+            p->velocity.x = (p->velocity.x * cloth->friction_factor);
+            p->velocity.y = -p->velocity.y * cloth->efficiency_factor;
         }
 
         // right
-        if (p->x > cloth->constraint_bottom_right.x) {
-            p->x = cloth->constraint_bottom_right.x;
-            p->velocity.x = -p->velocity.x*cloth->efficiency_factor;
+        if (p->pos.x >= cloth->constraint_bottom_right.x) {
+            p->pos.x = cloth->constraint_bottom_right.x;
+            p->velocity.x = -p->velocity.x * cloth->efficiency_factor;
         }
 
         // left
-        if (p->x < cloth->constraint_top_left.x) {
-            p->x = cloth->constraint_top_left.x;
-            p->velocity.x = -p->velocity.x*cloth->efficiency_factor;
+        if (p->pos.x <= cloth->constraint_top_left.x) {
+            p->pos.x = cloth->constraint_top_left.x;
+            p->velocity.x = -p->velocity.x * cloth->efficiency_factor;
         }
 
         // up
-        if (p->y < cloth->constraint_top_left.y) {
-            p->y = cloth->constraint_top_left.y;
-            p->velocity.y = -p->velocity.y*cloth->efficiency_factor;
+        if (p->pos.y <= cloth->constraint_top_left.y) {
+            p->pos.y = cloth->constraint_top_left.y;
+            p->velocity.y = -p->velocity.y * cloth->efficiency_factor;
         }
     }
 }

src/cloth.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "mouse.hpp"
 #include "point.hpp"
 #include "connection.hpp"
 #include "vec.hpp"
@@ -25,5 +26,4 @@ Cloth* new_cloth(
     Vec2 constraint_top_left, Vec2 constraint_bottom_right
 );
 void destroy_cloth(Cloth* cloth);
-void cloth_step(Cloth* cloth, Vec2f gravity_vec, float timedelta);
-void satisfy_cloth_constraints(Cloth* cloth);
+void cloth_step(Cloth* cloth, Mouse* mouse, Vec2f gravity_vec, float timedelta);

src/main.cpp

@@ -68,8 +68,9 @@ int main(const int argc, char** argv) {
         .cloth_startpos = Vec2{50, 50},
         .cloth_dimensions = Vec2{400, 400},
         .cloth_spacing = 20,
-        .gravity = Vec2f{0.65f, 0.45f},
+        .gravity = Vec2f{0.5f, 0.75f},
         .efficiency_factor = 0.25f,
+        .timestep = 1.0f,
         .background_color = RGB{205, 222, 242},
         .point_color = RGB{2, 10, 1},
         .point_selected_color = RGB{200, 40, 12},

src/mouse.cpp

@@ -0,0 +1,14 @@
+#include "mouse.hpp"
+
+Mouse* new_mouse(Vec2 position, float cursor_size) {
+    return new Mouse{
+        .left_button_clicked = false,
+        .cursor_radius_size = cursor_size,
+        .pos = position,
+        .last_pos = position,
+    };
+}
+
+void destroy_mouse(Mouse* mouse) {
+    delete mouse;
+}

src/mouse.hpp

@@ -0,0 +1,13 @@
+#pragma once
+
+#include "vec.hpp"
+
+struct Mouse {
+    bool left_button_clicked;
+    float cursor_radius_size;
+    Vec2 pos;
+    Vec2 last_pos;
+};
+
+Mouse* new_mouse(Vec2 position, float cursor_size);
+void destroy_mouse(Mouse* mouse);

src/point.hpp

@@ -4,10 +4,10 @@
 #include "vec.hpp"
 
 struct Point {
-    float x;
-    float y;
+    Vec2f pos;
     float mass;
     bool frozen;
     bool selected;
+    float radius;
     Vec2f velocity;
 };

src/window.cpp

@@ -60,9 +60,15 @@ void fill_screen(Window* window, RGB color) {
 }
 
 void draw_point(Window* window, Point point, RGB color) {
-    if (window->renderer != NULL) { 
+    if (window->renderer != NULL) {
         SDL_SetRenderDrawColor(window->renderer, color.r, color.g, color.b, 255);
-        SDL_RenderDrawPoint(window->renderer, (int) point.x, (int) point.y);
+        for (float angle = 0.0f; angle <= 6.283f; angle+=1.0f/point.radius ) {
+            SDL_RenderDrawPoint(
+            window->renderer,
+            point.pos.x+point.radius*cos(angle),
+            point.pos.y+point.radius*sin(angle) 
+            );
+        }
     }
 }
 
@@ -71,10 +77,10 @@ void draw_connection(Window* window, Connection connection, RGB color) {
         SDL_SetRenderDrawColor(window->renderer, color.r, color.g, color.b, 255);
         SDL_RenderDrawLine(
             window->renderer,
-            (int) connection.p0.x,
-            (int) connection.p0.y,
-            (int) connection.p1.x,
-            (int) connection.p1.y
+            (int) connection.p0.pos.x,
+            (int) connection.p0.pos.y,
+            (int) connection.p1.pos.x,
+            (int) connection.p1.pos.y
         );
     }
 }
@@ -85,6 +91,10 @@ void draw_cloth(Window* window, Cloth* cloth, RGB point_color, RGB connection_co
     }
 
     for (const Point* point : cloth->points) {
-        draw_point(window, *point, point_color);
+        if (point->selected) {
+            draw_point(window, *point, selected_p_color);
+        } else {
+            draw_point(window, *point, point_color);
+        }
     }
 }