#include<iostream>
#include<glad/glad.h>
#include<GLFW/glfw3.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
const char* vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"layout (location = 1) in vec3 aColour;"
"out vec3 vertexColour;\n"
"void main()\n"
"{\n"
"gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"vertexColour = aColour;\n"
"}\0";
const char* fragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;\n"
"in vec3 vertexColour;\n"
"void main()\n"
"{\n"
" FragColor = vec4(vertexColour,1.0f);\n"
"}\n\0";
// renderable classes
class Render {
};
class Quad : public Render {
public:
unsigned int VAO;
unsigned int VBO;
unsigned int IBO;
float vertices[24] = {
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 0.0f, // bottom left index -- 0
0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 0.0f, // bottom right index -- 1
-0.5f, 0.5f, 0.0f, 0.0f, 0.0f, 0.0f, // top left index -- 2
0.5f, 0.5f, 0.0f, 0.0f, 0.0f, 0.0f, // top right index -- 3
};
unsigned int indices[6] = {
0,1,2,
1,3,2
};
void constructVAO() {
glGenVertexArrays(1, &VAO);
glBindVertexArray(0);
constructVBO(); // Bind the VBO
constructIBO(); // Bind the IBO
// position VAO
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// colour VAO
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
};
void constructVBO() {
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
};
void constructIBO() {
glGenBuffers(1, &IBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
}
void quadForge() {
constructVBO();
constructIBO();
constructVAO();
}
};
int main() {
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(1920, 1080, "test", NULL, NULL);
glfwMakeContextCurrent(window);
gladLoadGL();
glViewport(0, 0, 1920, 1080);
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
unsigned int vertexShader;
vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
unsigned int fragmentShader;
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
unsigned int shaderProgram;
shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
Quad quad1;
quad1.quadForge();
glfwSwapBuffers(window);
while (!glfwWindowShouldClose(window)) {
glfwPollEvents();
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(shaderProgram);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glfwSwapBuffers(window);
}
glfwDestroyWindow(window);
glfwTerminate();
}
I've created a quad class and initialised an object to render. However, it simply doesn't render anything on the screen but was prior to putting it into an object
I do have these warnings
Severity Code Description Project File Line Suppression State
Warning C26495 Variable 'Quad::IBO' is uninitialized. Always initialize a member variable (type.6). OpenGLProject C:\\Users\\intel\\source\\repos\\OpenGLProject\\main.cpp 79
Warning C26495 Variable 'Quad::VAO' is uninitialized. Always initialize a member variable (type.6). OpenGLProject C:\\Users\\intel\\source\\repos\\OpenGLProject\\main.cpp 79
Warning C26495 Variable 'Quad::VBO' is uninitialized. Always initialize a member variable (type.6). OpenGLProject C:\\Users\\intel\\source\\repos\\OpenGLProject\\main.cpp 79
(although the variables are initialised)
I've tried to first to actually return the VAO's from the function and then assign them but these all gave back no results
Warning
Since uninitialized variables are used, the compiler gives a proper warning. The compiler does not know, that the functions will actually initialize them.
Compile and Link status
You don't check whether the shaders gets compiled nor that the linkage of the program is successful. I am not 100% sure if that's of concern but there is a \n missing at the end of line 3 in the vertex shader source.
If either compilation or linkage are not of success, the shader info log or program info log will tell you what went wrong.
Also of importance: glDebugMessageCallback (OpenGL 4.3+)
Redundant function calls
quadForge gets invoked, which invokes constructVBO, constructIBO and constructVAO, but the latter also invokes the previous functions (vbo, ibo). Seems redundant, no?
zero vertex array object
In the constructVAO function, you generate a vertex array object name, but instead of using the generated vertex array object name, you use the special vertex array object name zero (0), which is usually used to break the existing binding.
So, instead of glBindVertexArray(0) use glBindVertexArray(VAO)