Paul Terwilliger Paul Terwilliger - 2 months ago 11
C++ Question

Instancing millions of objects in OpenGL

My ultimate goal is to render 1 million spheres of different sizes and colors at 60 fps. I want to be able to move the camera around the screen as well.

I have modified the code on this page of the tutorial I am studying to try to instance 1 million cubes. I have been able to instance up to 90,000 cubes, but if I try to instance 160,000 cubes then the program breaks. I get an error that the program has "stopped working" and unexpectedly quit. I don't know what kind of error this is, but I believe that it may be memory related.

My understanding of instancing is naive, so I do not know what the problem is. I believe that instancing 1 million cubes is the next step to my goal of instancing 1 million spheres. So, my question: How do I instance 1 million cubes/objects in OpenGL?

I have been learning OpenGL through this tutorial and so I use 32-bit GLEW and 32-bit GLFW in Visual Studio 2013. I have 8 GB of RAM on a 64-bit operating system (Windows 7) with an 2.30 GHz CPU.

My code is below:

(set line #2 to be the number of cubes to be instanced. Make sure line#2 has a whole-number square root)

// Make sure NUM_INS is a square number
#define NUM_INS 9

// GLEW
#define GLEW_STATIC
#include <GL/glew.h>

// GLFW
#include <GLFW/glfw3.h>

// GL includes
#include "Shader.h"

// GLM Mathemtics
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

// Properties
GLuint screenWidth = 800, screenHeight = 600;

// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);


// The MAIN function, from here we start our application and run the Game loop
int main()
{
// Init GLFW
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

GLFWwindow* window = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr); // Windowed
glfwMakeContextCurrent(window);

// Set the required callback functions
glfwSetKeyCallback(window, key_callback);

// Initialize GLEW to setup the OpenGL Function pointers
glewExperimental = GL_TRUE;
glewInit();

// Define the viewport dimensions
glViewport(0, 0, screenWidth, screenHeight);

// Setup OpenGL options
//glEnable(GL_DEPTH_TEST);

// Setup and compile our shader(s)
Shader shader("core.vs", "core.frag");

// Generate a list of 100 quad locations/translation-vectors
glm::vec2 translations[NUM_INS];
int index = 0;
GLfloat offset = 1.0f/sqrt(NUM_INS);
for (GLint y = -sqrt(NUM_INS); y < sqrt(NUM_INS); y += 2)
{
for (GLint x = -sqrt(NUM_INS); x < sqrt(NUM_INS); x += 2)
{
glm::vec2 translation;
translation.x = (GLfloat)x / sqrt(NUM_INS) + offset;
translation.y = (GLfloat)y / sqrt(NUM_INS) + offset;
translations[index++] = translation;
}
}

// Store instance data in an array buffer
GLuint instanceVBO;
glGenBuffers(1, &instanceVBO);
glBindBuffer(GL_ARRAY_BUFFER, instanceVBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec2) * NUM_INS, &translations[0], GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);

// Generate quad VAO
GLfloat 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, 0.0f, 1.0f
};

GLfloat vertices[] = {
-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 1.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 1.0f, 1.0f, 0.0f,
-0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,
-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 0.0f, 1.0f,

-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.0f, 0.0f, 1.0f,
0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 1.0f, 0.0f,
-0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,
-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.0f, 0.0f, 1.0f,

-0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
-0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 1.0f, 1.0f, 0.0f,
-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,
-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,
-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.0f, 0.0f, 0.0f,
-0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,

0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 1.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.0f, 0.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,

-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 1.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.0f, 0.0f, 0.0f,
-0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,

-0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 1.0f, 1.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 1.0f, 0.0f, 0.0f,
-0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), 0.0f, 0.0f, 0.0f,
-0.5f/sqrt(NUM_INS), 0.5f/sqrt(NUM_INS), -0.5f/sqrt(NUM_INS), 0.0f, 1.0f, 0.0f
};

GLuint quadVAO, quadVBO;
glGenVertexArrays(1, &quadVAO);
glGenBuffers(1, &quadVBO);
glBindVertexArray(quadVAO);
glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(2 * sizeof(GLfloat)));
// Also set instance data
glEnableVertexAttribArray(2);
glBindBuffer(GL_ARRAY_BUFFER, instanceVBO);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(GLfloat), (GLvoid*)0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glVertexAttribDivisor(2, 1); // Tell OpenGL this is an instanced vertex attribute.
glBindVertexArray(0);


// Game loop
while (!glfwWindowShouldClose(window))
{
// Check and call events
glfwPollEvents();

// Clear buffers
glClearColor(0.03f, 0.03f, 0.03f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);

// Draw 100 instanced quads
shader.Use();
glBindVertexArray(quadVAO);
glDrawArraysInstanced(GL_TRIANGLES, 0, 36, NUM_INS); // 100 triangles of 6 vertices each
glBindVertexArray(0);

// Swap the buffers
glfwSwapBuffers(window);
}

glfwTerminate();
return 0;
}

// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
glfwSetWindowShouldClose(window, GL_TRUE);
}


Vertex Shader: (named core.vs)

#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 color;
layout (location = 2) in vec2 offset;

out vec3 fColor;

void main()
{
gl_Position = vec4(position.x + offset.x, position.y + offset.y, position.z, 1.0f);
fColor = color;
}


Fragment Shader: (named core.frag)

#version 330 core
in vec3 fColor;
out vec4 color;

void main()
{
color = vec4(fColor, 1.0f);
}


Shader class: (named Shader.h)

#pragma once

// Std. Includes
#include <vector>

// GL Includes
#include <GL/glew.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>



// Defines several possible options for camera movement. Used as abstraction to stay away from window-system specific input methods
enum Camera_Movement {
FORWARD,
BACKWARD,
LEFT,
RIGHT
};

// Default camera values
const GLfloat YAW = -90.0f;
const GLfloat PITCH = 0.0f;
const GLfloat SPEED = 3.0f;
const GLfloat SENSITIVTY = 0.25f;
const GLfloat ZOOM = 45.0f;


// An abstract camera class that processes input and calculates the corresponding Eular Angles, Vectors and Matrices for use in OpenGL
class Camera
{
public:
// Camera Attributes
glm::vec3 Position;
glm::vec3 Front;
glm::vec3 Up;
glm::vec3 Right;
glm::vec3 WorldUp;
// Eular Angles
GLfloat Yaw;
GLfloat Pitch;
// Camera options
GLfloat MovementSpeed;
GLfloat MouseSensitivity;
GLfloat Zoom;

// Constructor with vectors
Camera(glm::vec3 position = glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f), GLfloat yaw = YAW, GLfloat pitch = PITCH) : Front(glm::vec3(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVTY), Zoom(ZOOM)
{
this->Position = position;
this->WorldUp = up;
this->Yaw = yaw;
this->Pitch = pitch;
this->updateCameraVectors();
}
// Constructor with scalar values
Camera(GLfloat posX, GLfloat posY, GLfloat posZ, GLfloat upX, GLfloat upY, GLfloat upZ, GLfloat yaw, GLfloat pitch) : Front(glm::vec3(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVTY), Zoom(ZOOM)
{
this->Position = glm::vec3(posX, posY, posZ);
this->WorldUp = glm::vec3(upX, upY, upZ);
this->Yaw = yaw;
this->Pitch = pitch;
this->updateCameraVectors();
}

// Returns the view matrix calculated using Eular Angles and the LookAt Matrix
glm::mat4 GetViewMatrix()
{
return glm::lookAt(this->Position, this->Position + this->Front, this->Up);
}

// Processes input received from any keyboard-like input system. Accepts input parameter in the form of camera defined ENUM (to abstract it from windowing systems)
void ProcessKeyboard(Camera_Movement direction, GLfloat deltaTime)
{
GLfloat velocity = this->MovementSpeed * deltaTime;
if (direction == FORWARD)
this->Position += this->Front * velocity;
if (direction == BACKWARD)
this->Position -= this->Front * velocity;
if (direction == LEFT)
this->Position -= this->Right * velocity;
if (direction == RIGHT)
this->Position += this->Right * velocity;
}

// Processes input received from a mouse input system. Expects the offset value in both the x and y direction.
void ProcessMouseMovement(GLfloat xoffset, GLfloat yoffset, GLboolean constrainPitch = true)
{
xoffset *= this->MouseSensitivity;
yoffset *= this->MouseSensitivity;

this->Yaw += xoffset;
this->Pitch += yoffset;

// Make sure that when pitch is out of bounds, screen doesn't get flipped
if (constrainPitch)
{
if (this->Pitch > 89.0f)
this->Pitch = 89.0f;
if (this->Pitch < -89.0f)
this->Pitch = -89.0f;
}

// Update Front, Right and Up Vectors using the updated Eular angles
this->updateCameraVectors();
}

// Processes input received from a mouse scroll-wheel event. Only requires input on the vertical wheel-axis
void ProcessMouseScroll(GLfloat yoffset)
{
if (this->Zoom >= 1.0f && this->Zoom <= 45.0f)
this->Zoom -= yoffset;
if (this->Zoom <= 1.0f)
this->Zoom = 1.0f;
if (this->Zoom >= 45.0f)
this->Zoom = 45.0f;
}

private:
// Calculates the front vector from the Camera's (updated) Eular Angles
void updateCameraVectors()
{
// Calculate the new Front vector
glm::vec3 front;
front.x = cos(glm::radians(this->Yaw)) * cos(glm::radians(this->Pitch));
front.y = sin(glm::radians(this->Pitch));
front.z = sin(glm::radians(this->Yaw)) * cos(glm::radians(this->Pitch));
this->Front = glm::normalize(front);
// Also re-calculate the Right and Up vector
this->Right = glm::normalize(glm::cross(this->Front, this->WorldUp)); // Normalize the vectors, because their length gets closer to 0 the more you look up or down which results in slower movement.
this->Up = glm::normalize(glm::cross(this->Right, this->Front));
}
};

Answer

First, I must say that your Shader class is camera code, But I also learned from that tutorial, so simply change it by myself.

The problem you want to slove is relative your system heaps size. In visual stuido, only allowed you to make a local variable size in 1MB, and your program is overflow when setting NUM_INS to 160000.

To slove the problem, you could change the visual studio setting by following steps:

  1. right click on your project -> settings
  2. go to linker -> system
  3. set the heap reserved size to 2097152 (2M)

Note that my editor is Chinese, so I don't know exactly the name for the detail. By setting this, you could set NUM_INS to 160,000 or more and see the result like this:

Edit: This is not a good idea like @Matteo Italia said, but for testing, you could do this temporary. I'm not good at heap/stack knowledge, but I think the setting is heap reserve size , some relative post do the same job.