Now have anti-aliasing with framebuffers and can do post processing on it. Look at shaders/30-screen-bw.frag.glsl to see.

30-anti-aliasing/config.json

@@ -11,8 +11,8 @@
       "geometry_path": ""
     },
     "screen_shader": {
-      "vertex_path": "shaders/21-screen.vert.glsl",
+      "vertex_path": "shaders/30-screen.vert.glsl",
-      "frag_path": "shaders/21-screen.frag.glsl",
+      "frag_path": "shaders/30-screen.frag.glsl",
       "geometry_path": ""
     },
     "skybox_shader": {

30-anti-aliasing/shaders/30-screen-bw.frag.glsl

@@ -0,0 +1,13 @@
+#version 330 core
+out vec4 FragColor;
+
+in vec2 TexCoords;
+
+uniform sampler2D screenTexture;
+
+void main()
+{
+    vec3 col = texture(screenTexture, TexCoords).rgb;
+    float grayscale = 0.2126 * col.r + 0.7152 * col.g + 0.0722 * col.b;
+    FragColor = vec4(vec3(grayscale), 1.0);
+}

30-anti-aliasing/shaders/30-screen.frag.glsl

@@ -0,0 +1,11 @@
+#version 330 core
+out vec4 FragColor;
+
+in vec2 TexCoords;
+
+uniform sampler2D screenTexture;
+
+void main()
+{
+    FragColor = texture(screenTexture, TexCoords);
+}

30-anti-aliasing/shaders/30-screen.vert.glsl

@@ -0,0 +1,11 @@
+#version 330 core
+layout (location = 0) in vec2 aPos;
+layout (location = 1) in vec2 aTexCoords;
+
+out vec2 TexCoords;
+
+void main()
+{
+    gl_Position = vec4(aPos.x, aPos.y, 0.0, 1.0);
+    TexCoords = aTexCoords;
+}

30-anti-aliasing/src/framebuffer.cpp

@@ -3,15 +3,33 @@
 #include <GLFW/glfw3.h>
 
 void FrameBuffer::init() {
-  // target_fb config
-  glGenFramebuffers(1, &target_fb);
-  glBindFramebuffer(GL_FRAMEBUFFER, target_fb);
-
   // target_fb configuration
   // -------------------------
   glGenFramebuffers(1, &target_fb);
   glBindFramebuffer(GL_FRAMEBUFFER, target_fb);
 
+  // create the multisamples color attachment texture
+  glGenTextures(1, &texture_multi);
+  glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, texture_multi);
+  glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 4, GL_RGB, SCR_WIDTH, SCR_HEIGHT, GL_TRUE);
+  glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
+  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D_MULTISAMPLE, texture_multi, 0);
+
+  // create a renderbuffer object for depth and stencil attachment (we won't be sampling these)
+  glGenRenderbuffers(1, &target_rbo);
+  glBindRenderbuffer(GL_RENDERBUFFER, target_rbo);
+  glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_DEPTH24_STENCIL8, SCR_WIDTH, SCR_HEIGHT); // use a single renderbuffer object for both a depth AND stencil buffer.
+  glBindRenderbuffer(GL_RENDERBUFFER, 0);
+  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, target_rbo); // now actually attach it
+  // now that we actually created the target_fb and added all attachments we want to check if it is actually complete now
+
+  dbc::check(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE, "Frame buffer not complete.");
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+  // intermediate fbo here
+  glGenFramebuffers(1, &intermediate_fbo);
+  glBindFramebuffer(GL_FRAMEBUFFER, intermediate_fbo);
+
   // create a color attachment texture
   glGenTextures(1, &texture_buffer);
   glBindTexture(GL_TEXTURE_2D, texture_buffer);
@@ -20,13 +38,6 @@ void FrameBuffer::init() {
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture_buffer, 0);
 
-  // create a renderbuffer object for depth and stencil attachment (we won't be sampling these)
-  glGenRenderbuffers(1, &target_rbo);
-  glBindRenderbuffer(GL_RENDERBUFFER, target_rbo);
-  glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, SCR_WIDTH, SCR_HEIGHT); // use a single renderbuffer object for both a depth AND stencil buffer.
-  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, target_rbo); // now actually attach it
-  // now that we actually created the target_fb and added all attachments we want to check if it is actually complete now
-
   dbc::check(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE, "Frame buffer not complete.");
   glBindFramebuffer(GL_FRAMEBUFFER, 0);
 }
@@ -42,18 +53,20 @@ void FrameBuffer::begin() {
 
 void FrameBuffer::commit() {
   // disable the frame buffer
+  glBindFramebuffer(GL_READ_FRAMEBUFFER, target_fb);
+  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, intermediate_fbo);
+  glBlitFramebuffer(0, 0, SCR_WIDTH, SCR_HEIGHT, 0, 0, SCR_WIDTH, SCR_HEIGHT, GL_COLOR_BUFFER_BIT, GL_NEAREST);
   glBindFramebuffer(GL_FRAMEBUFFER, 0);
 }
 
 void FrameBuffer::draw(Screen& screen) {
-  glDisable(GL_DEPTH_TEST);
-
   glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
   glClear(GL_COLOR_BUFFER_BIT);
+  glDisable(GL_DEPTH_TEST);
 
-  // render the screen quad
   screen.shader.use();
   glBindVertexArray(screen.target_VAO);
+  glActiveTexture(GL_TEXTURE0);
   glBindTexture(GL_TEXTURE_2D, texture_buffer);
   glDrawArrays(GL_TRIANGLES, 0, 6);
 }

30-anti-aliasing/src/framebuffer.hpp

@@ -5,8 +5,10 @@
 
 struct FrameBuffer {
   unsigned int target_fb = 0;
+  unsigned int intermediate_fbo = 0;
   unsigned int target_rbo = 0;
   unsigned int texture_buffer = 0;
+  unsigned int texture_multi = 0;
 
   void init();
   void begin();

30-anti-aliasing/src/main.cpp

@@ -102,6 +102,7 @@ Scene setup() {
   glEnable(GL_DEPTH_TEST);
   glEnable(GL_BLEND);
   glEnable(GL_CULL_FACE);
+  glEnable(GL_MULTISAMPLE);
 
   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 

30-anti-aliasing/src/other_main.cpp

@@ -1,145 +0,0 @@
-#include <glad/glad.h>
-#include <GLFW/glfw3.h>
-
-#include "shader.hpp"
-
-#include <iostream>
-
-void framebuffer_size_callback(GLFWwindow* window, int width, int height);
-
-
-int main()
-{
-    // glfw: initialize and configure
-    // ------------------------------
-    glfwInit();
-    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
-    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
-    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-
-#ifdef __APPLE__
-    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
-#endif
-
-    // glfw window creation
-    // --------------------
-    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
-    if (window == NULL)
-    {
-        std::cout << "Failed to create GLFW window" << std::endl;
-        glfwTerminate();
-        return -1;
-    }
-    glfwMakeContextCurrent(window);
-
-    // glad: load all OpenGL function pointers
-    // ---------------------------------------
-    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
-    {
-        std::cout << "Failed to initialize GLAD" << std::endl;
-        return -1;
-    }
-
-    // configure global opengl state
-    // -----------------------------
-    glEnable(GL_DEPTH_TEST);
-
-    // build and compile shaders
-    // -------------------------
-    Shader shader({
-        .vertex_path="10.1.instancing.vs",
-        .frag_path="10.1.instancing.fs",
-        .geometry_path=""});
-
-    // generate a list of 100 quad locations/translation-vectors
-    // ---------------------------------------------------------
-    glm::vec2 translations[100];
-    int index = 0;
-    float offset = 0.1f;
-    for (int y = -10; y < 10; y += 2)
-    {
-        for (int x = -10; x < 10; x += 2)
-        {
-            glm::vec2 translation;
-            translation.x = (float)x / 10.0f + offset;
-            translation.y = (float)y / 10.0f + offset;
-            translations[index++] = translation;
-        }
-    }
-
-    // store instance data in an array buffer
-    // --------------------------------------
-    unsigned int instanceVBO;
-    glGenBuffers(1, &instanceVBO);
-    glBindBuffer(GL_ARRAY_BUFFER, instanceVBO);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec2) * 100, &translations[0], GL_STATIC_DRAW);
-    glBindBuffer(GL_ARRAY_BUFFER, 0);
-
-    // set up vertex data (and buffer(s)) and configure vertex attributes
-    // ------------------------------------------------------------------
-    float quadVertices[] = {
-        // positions     // colors
-        -0.05f,  0.05f,  1.0f, 0.0f, 0.0f,
-         0.05f, -0.05f,  0.0f, 1.0f, 0.0f,
-        -0.05f, -0.05f,  0.0f, 0.0f, 1.0f,
-
-        -0.05f,  0.05f,  1.0f, 0.0f, 0.0f,
-         0.05f, -0.05f,  0.0f, 1.0f, 0.0f,
-         0.05f,  0.05f,  0.0f, 1.0f, 1.0f
-    };
-    unsigned int quadVAO, quadVBO;
-    glGenVertexArrays(1, &quadVAO);
-    glGenBuffers(1, &quadVBO);
-    glBindVertexArray(quadVAO);
-    glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(quadVertices), quadVertices, GL_STATIC_DRAW);
-    glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
-    glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(2 * sizeof(float)));
-    // also set instance data
-    glEnableVertexAttribArray(2);
-    glBindBuffer(GL_ARRAY_BUFFER, instanceVBO); // this attribute comes from a different vertex buffer
-    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void*)0);
-    glBindBuffer(GL_ARRAY_BUFFER, 0);
-    glVertexAttribDivisor(2, 1); // tell OpenGL this is an instanced vertex attribute.
-
-
-    // render loop
-    // -----------
-    while (!glfwWindowShouldClose(window))
-    {
-        // render
-        // ------
-        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
-        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-
-        // draw 100 instanced quads
-        shader.use();
-        glBindVertexArray(quadVAO);
-        glDrawArraysInstanced(GL_TRIANGLES, 0, 6, 100); // 100 triangles of 6 vertices each
-        glBindVertexArray(0);
-
-        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
-        // -------------------------------------------------------------------------------
-        glfwSwapBuffers(window);
-        glfwPollEvents();
-    }
-
-    // optional: de-allocate all resources once they've outlived their purpose:
-    // ------------------------------------------------------------------------
-    glDeleteVertexArrays(1, &quadVAO);
-    glDeleteBuffers(1, &quadVBO);
-
-    glfwTerminate();
-    return 0;
-}
-
-// glfw: whenever the window size changed (by OS or user resize) this callback function executes
-// ---------------------------------------------------------------------------------------------
-void framebuffer_size_callback(GLFWwindow* window, int width, int height)
-{
-    // make sure the viewport matches the new window dimensions; note that width and
-    // height will be significantly larger than specified on retina displays.
-    glViewport(0, 0, width, height);
-}