Add translation, rotation and scale matrices

src/main.cc

@@ -1,4 +1,5 @@
 #include "glad/glad.h"
+#include "glm/ext/matrix_transform.hpp"
 #include "glm/gtc/type_ptr.hpp"
 #include "glm/trigonometric.hpp"
 #include <SDL2/SDL.h>
@@ -49,9 +50,14 @@ struct App {
   GLuint        shader_program;
 
   float         speed;
+  glm::mat4     translation;
+  glm::mat4     rotation;
+  glm::mat4     scale;
+
   // Model matrix to be sent as uniform to the vertex shader
   glm::mat4     model_mat;
   GLint         u_model_idx;
+  bool          recalc_model_mat;
 
   // Projection matrix to be sent as uniform to the vertex shader
   glm::mat4     projection_mat;
@@ -129,7 +135,10 @@ int init(App &app) {
   );
 
   app.speed          = 0.02f;
-  app.model_mat      = glm::translate(glm::mat4(1.0f), glm::vec3(0.0f));
+  app.translation    = glm::translate(glm::mat4(1.0f), glm::vec3(0.0f, 0.0f, -1.5f));
+  app.rotation       = glm::mat4(1.0f);
+  app.scale          = glm::mat4(1.0f);
+  app.model_mat      = app.translation * app.rotation * app.scale;
   app.projection_mat = glm::perspective(glm::radians(60.0f),
                                         (float)WINDOW_WIDTH / (float)WINDOW_HEIGHT,
                                         0.1f,
@@ -142,16 +151,16 @@ int init(App &app) {
 void create_vertex_spec(App &app) {
   const std::vector<GLfloat> vertices = {
     // vert0
-    -0.5f, -0.5f, -1.5f, // position
+    -0.5f, -0.5f, 0.0f, // position
      1.0f,  0.0f, 0.0f, // colour
     // vert1
-     0.5f, -0.5f, -1.5f, // position
+     0.5f, -0.5f, 0.0f, // position
      0.0f,  1.0f, 0.0f, // colour
     // vert2
-    -0.5f,  0.5f, -1.5f, // position
+    -0.5f,  0.5f, 0.0f, // position
      0.0f,  0.0f, 1.0f, // colour
     // vert3
-     0.5f,  0.5f, -1.5f, // position
+     0.5f,  0.5f, 0.0f, // position
      1.0f,  1.0f, 0.0f, // colour
   };
 
@@ -238,11 +247,38 @@ void run_main_loop(App &app) {
         app.running = false;
         break;
       case SDL_KEYDOWN:
-        if (app.event.key.keysym.sym == SDLK_UP) {
+        if (app.event.key.keysym.sym == SDLK_w) {
-          app.model_mat = glm::translate(app.model_mat, glm::vec3(0.0f, app.speed, 0.0f));
+          app.translation = glm::translate(app.translation, glm::vec3(0.0f, 0.0f, app.speed));
-        } else if (app.event.key.keysym.sym == SDLK_DOWN) {
+          app.recalc_model_mat = true;
-          app.model_mat = glm::translate(app.model_mat, glm::vec3(0.0f, -app.speed, 0.0f));
+        } else if (app.event.key.keysym.sym == SDLK_s) {
+          app.translation = glm::translate(app.translation, glm::vec3(0.0f, 0.0f, -app.speed));
+          app.recalc_model_mat = true;
+        } else if (app.event.key.keysym.sym == SDLK_d) {
+          app.translation = glm::translate(app.translation, glm::vec3(app.speed, 0.0f, 0.0f));
+          app.recalc_model_mat = true;
+        } else if (app.event.key.keysym.sym == SDLK_a) {
+          app.translation = glm::translate(app.translation, glm::vec3(-app.speed, 0.0f, 0.0f));
+          app.recalc_model_mat = true;
+        } else if (app.event.key.keysym.sym == SDLK_RIGHT) {
+          app.rotation = glm::rotate(app.rotation, glm::radians(10.0f), glm::vec3(0.0f, 1.0f, 0.0f));
+          app.recalc_model_mat = true;
+        } else if (app.event.key.keysym.sym == SDLK_LEFT) {
+          app.rotation = glm::rotate(app.rotation, glm::radians(-10.0f), glm::vec3(0.0f, 1.0f, 0.0f));
+          app.recalc_model_mat = true;
+        } else if (app.event.key.keysym.sym == SDLK_r) {
+          app.scale = glm::scale(app.scale, glm::vec3(1.2f));
+          app.recalc_model_mat = true;
+        } else if (app.event.key.keysym.sym == SDLK_e) {
+          app.scale = glm::scale(app.scale, glm::vec3(0.8f));
+          app.recalc_model_mat = true;
         }
+
+        if (app.recalc_model_mat) {
+          app.recalc_model_mat = false;
+          app.model_mat = app.translation * app.rotation * app.scale;
+        }
+
+        break;
       }
     }