Unable to get 3D view of rectangle in OpenGL - c++

Question

I am following this tutorial.
https://learnopengl.com/#!Getting-started/Coordinate-Systems - subtopic going 3D section i am not able to get the output only blank screen.
Here is my code:
#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include "shaders.h"
#include "camera.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
GLFWwindow* window;
GLuint VBO, VAO,EBO;
unsigned int texture;
const unsigned int screenwidth = 800;
const unsigned int screenheight = 600;
float vertices[] =
{
0.5f, 0.5f, 0.0f, 1.0f, 1.0f,
0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.0f, 0.0f, 1.0f
};
unsigned int indices[] =
{
0, 1, 3,
1, 2, 3
};
void glfwinitializer()
{
glfwInit();
window = glfwCreateWindow(screenwidth, screenheight, "Question 2 : Camera Space", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
}
glfwMakeContextCurrent(window);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
}
glEnable(GL_DEPTH_TEST);
}
void initializeVertex()
{
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glGenBuffers(1, &EBO);
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);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
void initializeTexture()
{
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
int width, height, nrChannels;
unsigned char *data = stbi_load("text.jpg", &width, &height, &nrChannels, 0);
if (data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
}
int main()
{
glfwinitializer();
Shader ourShader("vertexshader.vs", "fragmentshader.fs");
initializeVertex();
initializeTexture();
glm::mat4 projection(1);
projection = glm::perspective(glm::radians(45.0f), (float)screenwidth / (float)screenheight, 0.1f, 100.0f);
ourShader.setMat4("projection", projection);
while (!glfwWindowShouldClose(window))
{
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBindTexture(GL_TEXTURE_2D, texture);
ourShader.use();
glm::mat4 model(1);
model = glm::rotate(model, glm::radians(-55.f), glm::vec3(1.0f, 0.0f, 0.0f));
ourShader.setMat4("model", model);
glm::mat4 view(1);
view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
ourShader.setMat4("view", view);
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
glfwTerminate();
return 0;
}
My vertex shader is :
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoord;
out vec2 TexCoord;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection*view*model*vec4(aPos, 1.0);
TexCoord = vec2(aTexCoord.x,aTexCoord.y);
}
Trying to implement this code. I am getting blank output.
Output Image Here : No Rectangle
If I comment the three mode, view and projection matrix and remove from vertex shader file. . I am able to see the rectangle on the screen.
Output Image Here: Rectangle
I have one more question
glm::mat4 model(1);
glm::mat4 view(1);
glm::mat4 projection(1);
contains only value 1. When I am trying to comment following lines
//model = glm::rotate(model, glm::radians(-55.f), glm::vec3(1.0f, 0.0f, 0.0f));
//view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
//projection = glm::perspective(glm::radians(45.0f), (float)screenwidth / (float)screenheight, 0.1f, 100.0f);
and run the program without changing
gl_position = projection*view*model*vec4(aPos, 1.0);
I am getting blank screen

Answer 1

glUniformMatrix4fv specify the value of a uniform variable for the current program object.
This means glUseProgram has to be done before
glUniformMatrix4fv.
But you call
ourShader.setMat4("projection", projection);
before
ourShader.use();
so the uniform variable mat4 projection; is never set.
Change youre code somehow like this:
ourShader.use();
ourShader.setMat4("projection", projection);
I general your code is fine, except that you should use a minifying function for mipmaps:
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);