OpenGL/GLFW - scroll wheel not responding - c++

Question

I am following along with this tutorial series, but also trying to customise my solution as I go along (essentially I am trying to render a 3D point cloud -ie. a whole bunch of XYZ points).
I have been able to get the camera working and a 3D environment going. I am happy to work on the rest of that by myself, but the problem I am having is that the scroll wheel is not responding. I am hoping this is blindingly obvious to someone. It seems that the only user callback the program is getting is that of the mouse position - 100% of the time - and that's preventing the scroll_callback function form being heard. Can someone explain why my scroll wheel callback is not being received. Code below.
Let me know if any further info is required.
I am using Visual Studio 2017 Community.
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <Shader.h>
#include <iostream>
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);
// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 800;
// 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 firstMouse = true;
float yaw = -90.0f; // yaw is initialized to -90.0 degrees since a yaw of 0.0 results in a direction vector pointing to the right so we initially rotate a bit to the left.
float pitch = 0.0f;
float lastX = 800.0f / 2.0;
float lastY = 600.0 / 2.0;
float fov = 45.0f;
// timing
float deltaTime = 0.0f; // time between current frame and last frame
float lastFrame = 0.0f;
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);
//glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
// 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);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
glfwSetCursorPosCallback(window, mouse_callback);
glfwSetScrollCallback(window, scroll_callback);
// tell GLFW to capture our mouse
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
// 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);
Shader ourShader("VertexShader.vs", "FragShader.fs");
// set up vertex data (and buffer(s)) and configure vertex attributes
// ------------------------------------------------------------------
float vertices[] = {
-0.5f, -0.5f, 0.0f, // left
0.5f, -0.5f, 0.0f, // right
0.0f, 0.5f, 0.0f // top
};
struct Point
{
float x;
float y;
float z;
};
Point points[500];
for (int i = 0; i < 500; i++)
{
points[i].x = (float)((rand() % SCR_WIDTH) + 1);
points[i].y = (float)((rand() % SCR_WIDTH) + 1);
points[i].z = (float)((rand() % SCR_WIDTH) + 1);
// X Coords to Normalised Device coordinates
if (points[i].x > 400)
{
points[i].x = points[i].x * 0.00125f;
}
else if (points[i].x < 400)
{
points[i].x = points[i].x * -0.00125f;
}
else if (points[i].x == 400)
{
points[i].x = 0.0f;
}
// Y Coords to Normalised Device coordinates
if (points[i].y > 400)
{
points[i].y = points[i].y * 0.00125f;
}
else if (points[i].y < 400)
{
points[i].y = points[i].y * -0.00125f;
}
else if (points[i].y == 400)
{
points[i].y = 0.0f;
}
// Z Coords to Normalised Device coordinates
if (points[i].z > 400)
{
points[i].z = points[i].z * 0.00125f;
}
else if (points[i].z < 400)
{
points[i].z = points[i].z * -0.00125f;
}
else if (points[i].z == 400)
{
points[i].z = 0.0f;
}
//cout << points[i].x << ", " << points[i].y << ", " << points[i].z << endl;
}
unsigned int VBO, VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
// bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s).
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(points), points, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// note that this is allowed, the call to glVertexAttribPointer registered VBO as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind
glBindBuffer(GL_ARRAY_BUFFER, 0);
// You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other
// VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary.
glBindVertexArray(0);
// uncomment this call to draw in wireframe polygons.
//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
// render loop
// -----------
while (!glfwWindowShouldClose(window))
{
// input
// -----
processInput(window);
// render
// ------
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// activate shader
ourShader.use();
// create transformations
glm::mat4 projection;
projection = glm::perspective(glm::radians(95.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
ourShader.setMat4("projection", projection); // note: currently we set the projection matrix each frame, but since the projection matrix rarely changes it's often best practice to set it outside the main loop only once.
// camera/view transformation
glm::mat4 view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp);
ourShader.setMat4("view", view);
glm::mat4 model;
model = glm::rotate(model, glm::radians(-55.0f), glm::vec3(1.0f, 0.0f, 0.0f));
ourShader.setMat4("model", model);
// draw our points array
//glUseProgram(shaderProgram);
glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized
glPointSize(3.0f);
glDrawArrays(GL_POINTS, 0, 500);
// glBindVertexArray(0); // no need to unbind it every time
// 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, &VAO);
glDeleteBuffers(1, &VBO);
// glfw: terminate, clearing all previously allocated GLFW resources.
// ------------------------------------------------------------------
glfwTerminate();
return 0;
}
// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
float cameraSpeed = 2.5 * deltaTime;
if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
cameraPos += cameraSpeed * cameraFront;
if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
cameraPos -= cameraSpeed * cameraFront;
if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
cameraPos -= glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
cameraPos += glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
}
// 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);
}
// glfw: whenever the mouse moves, this callback is called
// -------------------------------------------------------
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
if (firstMouse)
{
lastX = xpos;
lastY = ypos;
firstMouse = false;
}
float xoffset = xpos - lastX;
float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top
lastX = xpos;
lastY = ypos;
float sensitivity = 0.1f; // change this value to your liking
xoffset *= sensitivity;
yoffset *= sensitivity;
yaw += xoffset;
pitch += yoffset;
// make sure that when pitch is out of bounds, screen doesn't get flipped
if (pitch > 89.0f)
pitch = 89.0f;
if (pitch < -89.0f)
pitch = -89.0f;
glm::vec3 front;
front.x = cos(glm::radians(yaw)) * cos(glm::radians(pitch));
front.y = sin(glm::radians(pitch));
front.z = sin(glm::radians(yaw)) * cos(glm::radians(pitch));
cameraFront = glm::normalize(front);
}
// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
if (fov >= 1.0f && fov <= 45.0f)
fov -= yoffset;
if (fov <= 1.0f)
fov = 1.0f;
if (fov >= 45.0f)
fov = 45.0f;
}

Answer 1

You're going to facepalm a little:
projection = glm::perspective(glm::radians(95.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
should be:
projection = glm::perspective(glm::radians(fov), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
I ran your code in a debugger and the scroll callback function is running every time but the fov value was never being used. You can use the same technique if you ever want to check if a function is being called by adding a break point anywhere in the function.