Rework RenderComponent to be more flexible

example/src/Cube.h

@@ -1,6 +1,7 @@
 #include <HandmadeMath.h>
 
 #include "Entity.h"
+#include "RenderComponent.h"
 
 #ifndef HMME_CUBE_H
 #define HMME_CUBE_H
@@ -86,24 +87,67 @@ static const GLfloat cubeColors[] = {
     0.982f,  0.099f,  0.879f
 };
 
+class CubeRenderComponent : public RenderComponent {
+public:
+    GLuint vaoID;
+    GLuint vertexBufferID;
+    GLuint colorBufferID;
+
+    CubeRenderComponent() {
+        glGenVertexArrays(1, &vaoID);
+
+        glGenBuffers(1, &vertexBufferID);
+        glBindBuffer(GL_ARRAY_BUFFER, vertexBufferID);
+        glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), cubeVertices, GL_STATIC_DRAW);
+
+        glGenBuffers(1, &colorBufferID);
+        glBindBuffer(GL_ARRAY_BUFFER, colorBufferID);
+        glBufferData(GL_ARRAY_BUFFER, sizeof(cubeColors), cubeColors, GL_STATIC_DRAW);
+    }
+
+    void Draw() override {
+        glBindVertexArray(vaoID);
+
+        // 1st attribute buffer : vertices
+        glEnableVertexAttribArray(0);
+        glBindBuffer(GL_ARRAY_BUFFER, vertexBufferID);
+        glVertexAttribPointer(
+           0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
+           3,                  // size
+           GL_FLOAT,           // type
+           GL_FALSE,           // normalized?
+           0,                  // stride
+           (void*)0            // array buffer offset
+        );
+
+        // 2nd attribute buffer : colors
+        glEnableVertexAttribArray(1);
+        glBindBuffer(GL_ARRAY_BUFFER, colorBufferID);
+        glVertexAttribPointer(
+            1,                 // attribute. No particular reason for 1, but must match the layout in the shader.
+            3,                 // size
+            GL_FLOAT,          // type
+            GL_FALSE,          // normalized?
+            0,                 // stride
+            (void*)0           // array buffer offset
+        );
+        
+        // Shader??
+
+        // Draw the triangle!
+        glDrawArrays(GL_TRIANGLES, 0, 36); // Starting from vertex 0; 3 vertices total -> 1 triangle
+        glDisableVertexAttribArray(0);
+        glDisableVertexAttribArray(1);
+    }
+};
+
 class Cube : public Entity {
 public:
     float x = 0;
+    CubeRenderComponent rc = CubeRenderComponent();
 
     Cube() {
-        Entity::RenderComponent c;
+        renderComponent = &rc;
-
-        glGenVertexArrays(1, &c.vaoID);
-
-        glGenBuffers(1, &c.vertexBufferID);
-        glBindBuffer(GL_ARRAY_BUFFER, c.vertexBufferID);
-        glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), cubeVertices, GL_STATIC_DRAW);
-
-        glGenBuffers(1, &c.colorBufferID);
-        glBindBuffer(GL_ARRAY_BUFFER, c.colorBufferID);
-        glBufferData(GL_ARRAY_BUFFER, sizeof(cubeColors), cubeColors, GL_STATIC_DRAW);
-
-        renderComponent = c;
     }
 
     void Tick(float deltaSeconds) override {

example/src/Entity.h

@@ -5,6 +5,8 @@
 #ifndef HMME_ENTITY_H
 #define HMME_ENTITY_H
 
+#include "RenderComponent.h"
+
 class Entity {
 public:
     hmm_vec3 position = HMM_Vec3(0.0f, 0.0f, 0.0f);
@@ -19,12 +21,7 @@ public:
 
     virtual void Tick(float deltaSeconds) {}
 
-    struct RenderComponent {
+    RenderComponent *renderComponent = NULL;
-        GLuint vaoID;
-        GLuint vertexBufferID;
-        GLuint colorBufferID;
-    };
-    RenderComponent renderComponent;
 
     // Context for rendering and stuff
     hmm_mat4 modelMatrix;

example/src/RenderComponent.h

@@ -0,0 +1,13 @@
+#include <HandmadeMath.h>
+
+#ifndef HMME_RENDER_COMPONENT_H
+#define HMME_RENDER_COMPONENT_H
+
+#include "Entity.h"
+
+class RenderComponent {
+public:
+    virtual void Draw() = 0;
+};
+
+#endif

example/src/main.cpp

@@ -85,6 +85,7 @@ int main()
         hmm_mat4 view = HMM_LookAt(HMM_Vec3(3.0f, 3.0f, 4.0f), HMM_Vec3(0.0f, 0.0f, 0.0f), HMM_Vec3(0.0f, 1.0f, 0.0f));
         hmm_mat4 vp = projection * view;
 
+        // Tick
         auto now = high_resolution_clock::now();
         if (hasTicked) {
             auto elapsedNanoseconds = std::chrono::duration_cast<std::chrono::nanoseconds>(now - lastTickTime).count();
@@ -94,58 +95,23 @@ int main()
         lastTickTime = now;
         hasTicked = true;
 
+        // Compute model positions for rendering
         ComputeModelMatrices(&root, HMM_Mat4d(1.0f));
 
+        // Render!
         auto it = EntityIterator(&root);
-
         while (it.HasNext()) {
             Entity *e = it.Next();
 
-            if (!e->renderComponent.vaoID) {
+            if (e->renderComponent) {
-                continue;
+                // Use our shader
+                glUseProgram(programID);
+
+                hmm_mat4 mvp = vp * e->modelMatrix;
+                glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &mvp.Elements[0][0]);
+
+                e->renderComponent->Draw();
             }
-
-            Entity::RenderComponent rc = e->renderComponent;
-
-            glBindVertexArray(rc.vaoID);
-
-            // 1st attribute buffer : vertices
-            glEnableVertexAttribArray(0);
-            glBindBuffer(GL_ARRAY_BUFFER, rc.vertexBufferID);
-            glVertexAttribPointer(
-               0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
-               3,                  // size
-               GL_FLOAT,           // type
-               GL_FALSE,           // normalized?
-               0,                  // stride
-               (void*)0            // array buffer offset
-            );
-
-            // 2nd attribute buffer : colors
-            glEnableVertexAttribArray(1);
-            glBindBuffer(GL_ARRAY_BUFFER, rc.colorBufferID);
-            glVertexAttribPointer(
-                1,                                // attribute. No particular reason for 1, but must match the layout in the shader.
-                3,                                // size
-                GL_FLOAT,                         // type
-                GL_FALSE,                         // normalized?
-                0,                                // stride
-                (void*)0                          // array buffer offset
-            );
-            
-            // Use our shader
-            glUseProgram(programID);
-
-            hmm_mat4 mvp = vp * e->modelMatrix;
-
-            // Send our transformation to the currently bound shader, in the "MVP" uniform
-            // This is done in the main loop since each model will have a different MVP matrix (At least for the M part)
-            glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &mvp.Elements[0][0]);
-
-            // Draw the triangle!
-            glDrawArrays(GL_TRIANGLES, 0, 36); // Starting from vertex 0; 3 vertices total -> 1 triangle
-            glDisableVertexAttribArray(0);
-            glDisableVertexAttribArray(1);
         }
 
         // Swap buffers