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

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This commit is contained in:
Zed A. Shaw 2026-09-11 14:33:20 -04:00
parent 9ce217e0e2
commit 1830faf4c9
8 changed files with 67 additions and 161 deletions
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4
30-anti-aliasing/config.json
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@ -11,8 +11,8 @@
"geometry_path": ""
},
"screen_shader": {
"vertex_path": "shaders/21-screen.vert.glsl",
"frag_path": "shaders/21-screen.frag.glsl",
"vertex_path": "shaders/30-screen.vert.glsl",
"frag_path": "shaders/30-screen.frag.glsl",
"geometry_path": ""
},
"skybox_shader": {

13
30-anti-aliasing/shaders/30-screen-bw.frag.glsl Normal file
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@ -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);
}

11
30-anti-aliasing/shaders/30-screen.frag.glsl Normal file
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@ -0,0 +1,11 @@
#version 330 core
out vec4 FragColor;
in vec2 TexCoords;
uniform sampler2D screenTexture;
void main()
{
FragColor = texture(screenTexture, TexCoords);
}

11
30-anti-aliasing/shaders/30-screen.vert.glsl Normal file
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@ -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;
}

41
30-anti-aliasing/src/framebuffer.cpp
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@ -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);
}

2
30-anti-aliasing/src/framebuffer.hpp
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@ -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();

1
30-anti-aliasing/src/main.cpp
View file

@ -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);

145
30-anti-aliasing/src/other_main.cpp
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@ -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);
}