OpenGL First Person Camera Doesn't Move - c++

Question

I have created a simple cube in OpenGL, and am still coming to grips with developing an FPS camera to move around it. For now, the code only allows for left, right, up and down movements via the W,A,S,D keys. The application code is as follows:
#include <iostream>
#include <cmath>
// GLEW
#define GLEW_STATIC
#include <GL/glew.h>
// GLFW
#include <GLFW/glfw3.h>
// GLM Mathematics
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
// Other includes
#include "Shader.h"
// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void do_movement();
// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;
// Camera
glm::vec3 cameraPos = glm::vec3(0.0f, 0.0f, 3.0f);
glm::vec3 cameraFront = glm::vec3(0.0f, 0.0f, -1.0f);
glm::vec3 cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);
bool keys[1024];
// Deltatime
GLfloat deltaTime = 0.0f; // Time between current frame and last frame
GLfloat lastFrame = 0.0f; // Time of last frame
// The MAIN function, from here we start the application and run the game loop
int main()
{
// Init GLFW
glfwInit();
// Set all the required options for GLFW
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);
// Create a GLFWwindow object that we can use for GLFW's functions
GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
glfwMakeContextCurrent(window);
// Set the required callback functions
glfwSetKeyCallback(window, key_callback);
// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
glewExperimental = GL_TRUE;
// Initialize GLEW to setup the OpenGL Function pointers
glewInit();
// Define the viewport dimensions
glViewport(0, 0, WIDTH, HEIGHT);
//Enable depth test
glEnable(GL_DEPTH_TEST);
// Build and compile our shader program
Shader ourShader("C:/Users/Noel/Documents/Visual Studio 2013/Projects/RoomSim/Vertexshader.vs", "C:/Users/Noel/Documents/Visual Studio 2013/Projects/RoomSim/FragShader.frag");
// Set up vertex data (and buffer(s)) and attribute pointers
GLfloat vertices[] = {
-0.5f, -0.5f, -0.5f,
0.5f, -0.5f, -0.5f,
0.5f, 0.5f, -0.5f,
0.5f, 0.5f, -0.5f,
-0.5f, 0.5f, -0.5f,
-0.5f, -0.5f, -0.5f,
-0.5f, -0.5f, 0.5f,
0.5f, -0.5f, 0.5f,
0.5f, 0.5f, 0.5f,
0.5f, 0.5f, 0.5f,
-0.5f, 0.5f, 0.5f,
-0.5f, -0.5f, 0.5f,
-0.5f, 0.5f, 0.5f,
-0.5f, 0.5f, -0.5f,
-0.5f, -0.5f, -0.5f,
-0.5f, -0.5f, -0.5f,
-0.5f, -0.5f, 0.5f,
-0.5f, 0.5f, 0.5f,
0.5f, 0.5f, 0.5f,
0.5f, 0.5f, -0.5f,
0.5f, -0.5f, -0.5f,
0.5f, -0.5f, -0.5f,
0.5f, -0.5f, 0.5f,
0.5f, 0.5f, 0.5f,
-0.5f, -0.5f, -0.5f,
0.5f, -0.5f, -0.5f,
0.5f, -0.5f, 0.5f,
0.5f, -0.5f, 0.5f,
-0.5f, -0.5f, 0.5f,
-0.5f, -0.5f, -0.5f,
-0.5f, 0.5f, -0.5f,
0.5f, 0.5f, -0.5f,
0.5f, 0.5f, 0.5f,
0.5f, 0.5f, 0.5f,
-0.5f, 0.5f, 0.5f,
-0.5f, 0.5f, -0.5f,
};
GLuint VBO, VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
// Bind the Vertex Array Object first, then bind and set vertex buffer(s) and attribute pointer(s).
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
//glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
// Position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3* sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(0);
// Color attribute
//glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
//glEnableVertexAttribArray(1);
glBindVertexArray(0); // Unbind VAO
// Game loop
while (!glfwWindowShouldClose(window))
{
// Calculate deltatime of current frame
GLfloat currentFrame = glfwGetTime();
deltaTime = currentFrame - lastFrame;
lastFrame = currentFrame;
// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
glfwPollEvents();
do_movement();
// Render
// Clear the colorbuffer
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//Transformations
// Create transformations
//glm::mat4 transform;
//transform = glm::translate(transform, glm::vec3(0.5f, -0.5f, 0.0f));
//transform = glm::rotate(transform, (GLfloat)glfwGetTime() * 50.0f, glm::vec3(0.0f, 0.0f, 1.0f));
// Get matrix's uniform location and set matrix
//GLint transformLoc = glGetUniformLocation(ourShader.Program, "transform");
//glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(transform));
// Draw the triangle
ourShader.Use();
// Create transformations
glm::mat4 model;
glm::mat4 view;
glm::mat4 projection;
//Camera particulars for view
glm::vec3 cameraPos = glm::vec3(0.0f, 0.0f, 3.0f);
glm::vec3 cameraFront = glm::vec3(0.0f, 0.0f, -1.0f);
glm::vec3 cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);
model = glm::rotate(model, 50.0f, glm::vec3(1.0f, 0.0f, 0.0f));
view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp);
projection = glm::perspective(45.0f, (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);
// Get their uniform location
GLint modelLoc = glGetUniformLocation(ourShader.Program, "model");
GLint viewLoc = glGetUniformLocation(ourShader.Program, "view");
GLint projLoc = glGetUniformLocation(ourShader.Program, "projection");
glBindVertexArray(VAO);
// Pass them to the shaders
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
glDrawArrays(GL_TRIANGLES, 0, 36);
glBindVertexArray(0);
// Swap the screen buffers
glfwSwapBuffers(window);
}
// Properly de-allocate all resources once they've outlived their purpose
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
// Terminate GLFW, clearing any resources allocated by GLFW.
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);
if (key >= 0 && key < 1024)
{
if (action == GLFW_PRESS)
keys[key] = true;
else if (action == GLFW_RELEASE)
keys[key] = false;
}
}
void do_movement()
{
GLfloat cameraSpeed = 5.0f * deltaTime;
// Camera controls
if (keys[GLFW_KEY_W])
cameraPos += cameraSpeed * cameraFront;
if (keys[GLFW_KEY_S])
cameraPos -= cameraSpeed * cameraFront;
if (keys[GLFW_KEY_A])
cameraPos -= glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
if (keys[GLFW_KEY_D])
cameraPos += glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
}
The issue is that nothing happens on pressing the W,A,S,D keys whatsover. The Vertex shader implemented is as below:
#version 330 core
layout(location = 0) in vec3 position;
layout(location = 1) in vec3 color;
out vec3 ourColor;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection * view * model * vec4(position, 1.0f);
ourColor = color;
}
What could be the cause for no movement?

Answer 1

You redefine cameraPos inside the while loop, this shadows the global cameraPos you update in the doMovement function.
Just remove the declarations from inside the while.

Answer 2

There are two variables called cameraPos:
One in global scope which is used in key_callback
and a local one in main (inside the while loop) which is set to a constant value and is used to create the view-matrix.
Solution: Remove the local variable in main and just use the global one.