feat: implement dynamic framebuffer resizing for postprocessing

Author: AhmedSobhy01

src/common/systems/forward-renderer.cpp

@@ -5,6 +5,24 @@
 
 namespace our {
 
+    void ForwardRenderer::resizePostprocess(glm::ivec2 size) {
+        if (!postprocessMaterial) return;
+
+        glBindFramebuffer(GL_FRAMEBUFFER, postprocessFrameBuffer);
+
+        colorTarget->bind();
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, size.x, size.y, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTarget->getOpenGLName(), 0);
+
+        depthTarget->bind();
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT24, size.x, size.y, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT,
+                     nullptr);
+        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthTarget->getOpenGLName(), 0);
+
+        Texture2D::unbind();
+        glBindFramebuffer(GL_FRAMEBUFFER, 0);
+    }
+
     void ForwardRenderer::initialize(glm::ivec2 windowSize, const nlohmann::json& config) {
         // First, we store the window size for later use
         this->windowSize = windowSize;
@@ -54,21 +72,8 @@ namespace our {
         // Then we check if there is a postprocessing shader in the configuration
         if (config.contains("postprocess")) {
             glGenFramebuffers(1, &postprocessFrameBuffer);
-            glBindFramebuffer(GL_FRAMEBUFFER, postprocessFrameBuffer);
             colorTarget = new Texture2D();
-            colorTarget->bind();
-            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, windowSize.x, windowSize.y, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
-            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTarget->getOpenGLName(),
-                                   0);
-            colorTarget->unbind();
-
             depthTarget = new Texture2D();
-            depthTarget->bind();
-            glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT24, windowSize.x, windowSize.y, 0, GL_DEPTH_COMPONENT,
-                         GL_UNSIGNED_INT, nullptr);
-            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthTarget->getOpenGLName(), 0);
-            depthTarget->unbind();
-            glBindFramebuffer(GL_FRAMEBUFFER, 0);
 
             // Create a vertex array to use for drawing the texture
             glGenVertexArrays(1, &postProcessVertexArray);
@@ -94,6 +99,8 @@ namespace our {
             // The default options are fine but we don't need to interact with the depth buffer
             // so it is more performant to disable the depth mask
             postprocessMaterial->pipelineState.depthMask = false;
+
+            resizePostprocess(windowSize);
         }
     }
 
@@ -125,7 +132,13 @@ namespace our {
         }
     }
 
-    void ForwardRenderer::render(World* world) {
+    void ForwardRenderer::render(World* world, glm::ivec2 windowSize) {
+        if (windowSize.x <= 0 || windowSize.y <= 0) return;
+        if (this->windowSize != windowSize) {
+            this->windowSize = windowSize;
+            resizePostprocess(windowSize);
+        }
+
         // First of all, we search for a camera and for all the mesh renderers
         CameraComponent* camera = nullptr;
         opaqueCommands.clear();

src/common/systems/forward-renderer.hpp

@@ -42,14 +42,16 @@ namespace our {
         Texture2D *colorTarget, *depthTarget;
         TexturedMaterial* postprocessMaterial;
 
+        void resizePostprocess(glm::ivec2 size);
+
     public:
         // Initialize the renderer including the sky and the Postprocessing objects.
         // windowSize is the width & height of the window (in pixels).
         void initialize(glm::ivec2 windowSize, const nlohmann::json& config);
         // Clean up the renderer
         void destroy();
         // This function should be called every frame to draw the given world
-        void render(World* world);
+        void render(World* world, glm::ivec2 windowSize);
     };
 
 }  // namespace our

src/states/play-state.hpp

@@ -101,7 +101,7 @@ class Playstate : public our::State {
         enemySpawner.update(&world, (float)deltaTime);
         // And finally we use the renderer system to draw the scene
         collisionSystem.update(&world);
-        renderer.render(&world);
+        renderer.render(&world, getApp()->getFrameBufferSize());
 
 #ifdef COLLISION_DEBUG_DRAW
         // Toggle debug draw with F3

src/states/renderer-test-state.hpp

@@ -31,10 +31,11 @@ class RendererTestState : public our::State {
 
     void onDraw(double deltaTime) override {
         // We simply call the renderer's "render" function and it should do all the rendering work
-        renderer.render(&world);
+        renderer.render(&world, getApp()->getFrameBufferSize());
     }
 
     void onDestroy() override {
+        renderer.destroy();
         world.clear();
         our::clearAllAssets();
     }