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#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <random>
#include <chrono>
#include <memory>
#include "graphic_shader.h"
#include "compute_shader.h"
#include "texture_buffer.h"
#include "particle_vertex_buffer.h"
#include "shader/vertex.glsl"
#include "shader/fragment.glsl"
#include "shader/compute.glsl"
const std::size_t particle_count = 100000;
int window_width = 800;
int window_height = 600;
float world_width, world_height;
glm::mat4 MVP;
std::unique_ptr<TextureBuffer> textureBuffer;
std::unique_ptr<ParticleVertexBuffer> particleBuffer;
void updateMVP() {
world_width = 20.f;
world_height = world_width / window_width * window_height;
glm::mat4 projection = glm::ortho(
-(world_width /2), world_width/2,
-(world_height/2), world_height/2,
0.1f, 100.0f
);
glm::mat4 view = glm::lookAt(
glm::vec3(0,0,20),
glm::vec3(0,0,0),
glm::vec3(0,1,0)
);
glm::mat4 model = glm::mat4(1.0f);
MVP = projection * view * model;
}
void window_size_callback(GLFWwindow*, int width, int height) {
window_width = width;
window_height = height;
textureBuffer->resize(width, height);
updateMVP();
}
std::vector<GLfloat> makeInitialParticles(std::size_t count) {
std::vector<GLfloat> buffer;
buffer.reserve(3*count);
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_real_distribution<GLfloat> distX(-world_width/2., world_width/2.);
std::uniform_real_distribution<GLfloat> distY(-world_height/2., world_height/2.);
std::uniform_real_distribution<GLfloat> distAge(0., 5.);
for ( std::size_t i = 0; i < count; ++i ) {
buffer.emplace_back(distX(gen));
buffer.emplace_back(distY(gen));
buffer.emplace_back(distAge(gen));
}
return buffer;
}
int main() {
if( !glfwInit() ) {
std::cerr << "Failed to initialize GLFW" << std::endl;
return -1;
}
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* const window = glfwCreateWindow(window_width, window_height, "computicle", NULL, NULL);
if( window == nullptr ){
std::cerr << "Failed to open GLFW window." << std::endl;
glfwTerminate();
return -1;
}
glfwSetWindowSizeCallback(window, window_size_callback);
glfwMakeContextCurrent(window);
if ( glewInit() != GLEW_OK ) {
std::cerr << "Failed to initialize GLEW" << std::endl;
glfwTerminate();
return -1;
}
glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);
updateMVP();
GraphicShader sceneShader(VERTEX_SHADER_CODE, FRAGMENT_SHADER_CODE);
GraphicShader displayShader(R"(
#version 330 core
layout (location = 0) in vec2 screen_vertex;
layout (location = 1) in vec2 texture_vertex;
out vec2 TexCoords;
void main() {
gl_Position = vec4(screen_vertex, 0.0, 1.0);
TexCoords = texture_vertex;
}
)", R"(
#version 330 core
out vec4 FragColor;
in vec2 TexCoords;
uniform sampler2D screen_texture;
void main() {
FragColor = texture(screen_texture, TexCoords);
}
)");
sceneShader.setUniform("MVP", MVP);
displayShader.setUniform("screen_texture", 0);
textureBuffer = std::make_unique<TextureBuffer>(window_width, window_height);
particleBuffer = std::make_unique<ParticleVertexBuffer>(
makeInitialParticles(particle_count));
ComputeShader computeShader(COMPUTE_SHADER_CODE);
computeShader.workOn(particleBuffer->getBuffer());
const std::vector<GLfloat> quad_buffer_data{
-1.f, 1.f, 0.f, 1.f,
-1.f, -1.f, 0.f, 0.f,
1.f, -1.f, 1.f, 0.f,
-1.f, 1.f, 0.f, 1.f,
1.f, -1.f, 1.f, 0.f,
1.f, 1.f, 1.f, 1.f
};
GLuint QuadVertexArrayID;
GLuint QuadVertexBufferID;
glGenVertexArrays(1, &QuadVertexArrayID);
glGenBuffers(1, &QuadVertexBufferID);
glBindVertexArray(QuadVertexArrayID);
glBindBuffer(GL_ARRAY_BUFFER, QuadVertexBufferID);
glBufferData(
GL_ARRAY_BUFFER,
quad_buffer_data.size() * sizeof(GLfloat),
quad_buffer_data.data(),
GL_STATIC_DRAW
);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4*sizeof(GLfloat), (void*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4*sizeof(GLfloat), (void*)(2*sizeof(GLfloat)));
auto lastFrame = std::chrono::high_resolution_clock::now();
do {
// update particles at most 50 times per second
if ( std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::high_resolution_clock::now() - lastFrame).count() >= 20 ) {
auto guard = computeShader.use();
computeShader.setUniform("world", world_width, world_height);
computeShader.dispatch(particle_count);
lastFrame = std::chrono::high_resolution_clock::now();
}
{
auto texGuard = textureBuffer->use();
auto sdrGuard = sceneShader.use();
glClear(GL_COLOR_BUFFER_BIT);
sceneShader.setUniform("MVP", MVP);
particleBuffer->draw();
}
{
auto guard = displayShader.use();
glBindVertexArray(QuadVertexArrayID);
glBindTexture(GL_TEXTURE_2D, textureBuffer->getTexture());
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 6);
}
glfwSwapBuffers(window);
glfwPollEvents();
}
while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
glfwWindowShouldClose(window) == 0 );
glfwTerminate();
return 0;
}
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