Passing coordinate array to main (openGL, C++) - c++

I am trying to pass coordinates of a cube to a main function in C++. This function is located in a seperate cpp file and the method looks like this:
GLfloat * Cube::getVertices()
{
// Set up our vertex data (and buffer(s)) and attribute pointers
GLfloat vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};
// GLfloat *vert = vertices;
return vertices;
}
In the main method I do this
Cube cube1;
GLfloat * vertices;
vertices = cube1.getVertices();
Whenever my coordinates are in main the cube comes out correctly but when it is in this seperate method it seems like I am getting addresses instead of values and no square appears. Does it have something to do with the way I pass the array?


In this case you seem to have constant data that you want to return. Make it static and const. Then it won't go out of scope.
const GLfloat* Cube::getVertices() {
static const GLfloat vertices[] = {
// Data here.
};
return vertices;
}


Does it have something to do with the way I pass the array?
You don't pass an array. You pass a pointer. To a local array, those lifetime ends when the function is left. What you have here is just undefined behavior.

Related

How to subdivide Plane in OpenGL?

I want to generate VBO and EBO for subdivided plane, I draw with GL_TRIANGLES, I want to know effective way to do this.
Eventually it will be a huge cube consists from 6 subdivided plane, so, i can't imagine alghorithm to generate VBO and EBO for subdivide.
What i have as input data:
cube
std::vector<float> vertices =
{
// +Y SIDE //Colors
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
// -Y SIDE
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
// +X SIDE
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
// -X SIDE
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
// +Z SIDE
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
// -Z SIDE
-0.5f, 0.5f, -0.5f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 0.0f, 1.0f
};
std::vector<unsigned int> indices =
{
// +Y
1, 2, 0, 3, 2, 1,
// -Y
4, 6, 5, 5, 6, 7,
// +X
8, 9, 10, 9, 11, 10,
// -X
14, 13, 12, 14, 15, 13,
// +Z
17, 18, 16, 19, 18, 17,
// -Z
20, 22, 21, 21, 22, 23
};
So, i want to write a function witch accept subdivision and change my indeces and vertices vectors, just loop over existed planes in cube and subdivide it

Cube getting squashed and rendering as trapezium

I'm trying to render a cube and rotate it along it's Y axis using OpenGL ES 2.0, however the cube does not render as a cube but rather as some sort of very flat trapezium. A few images showing the odd behaviour:
Very flat:
beginning to rotate:
mid-rotation:
and after rotation:
I'm not exactly sure what is causing the strange behaviour. I am utilising the Pigs in a Blanket library for rendering on PS Vita.
These are my cube vertices. The first 3 values in each row are the vertex data, the last 2 values are for texture mapping
GLfloat vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};
This is my initialization function. surface_width = 960, surface_height = 544 and aspect = 1.764706
void TestScene::init(EGLint s_width, EGLint s_height)
{
surface_height = s_height;
surface_width = s_width;
model = glm::mat4(1.0f);
projection = glm::mat4(1.0f);
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
texture.load_texture("app0:assets/wall.jpg");
if (!shader.load_shaders("app0:shaders/vert.cg", "app0:shaders/frag.cg"))
sceKernelExitProcess(0);
}
This is my rendering function
void TestScene::render(EGLDisplay display, EGLSurface surface, double deltaTime)
{
glViewport(0, 0, surface_width, surface_height);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glEnable(GL_DEPTH_TEST);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture.ID);
glUseProgram(shader.ID);
GLint mvpLoc = glGetUniformLocation(shader.ID, "mvp");
GLint position = glGetAttribLocation(shader.ID, "vPosition");
GLint texLoc = glGetAttribLocation(shader.ID, "vTexCoord");
GLfloat aspect = (GLfloat)surface_width/(GLfloat)surface_height;
projection = glm::perspective(glm::radians(camera.Zoom), aspect, 0.1f, 100.0f);
view = camera.GetViewMatrix();
model = glm::rotate(model, glm::radians(1.0f), glm::vec3(0.0f, -1.0f, 0.0f));
glm::mat4 mvp = projection * view * model;
glUniformMatrix4fv(mvpLoc, 1, GL_FALSE, glm::value_ptr(mvp));
// Bind vertex positions
glEnableVertexAttribArray(position);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
// Bind texture positions
glEnableVertexAttribArray(texLoc);
glVertexAttribPointer(texLoc, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glDrawArrays(GL_TRIANGLES, 0, 36);
glDisableVertexAttribArray(position);
glDisableVertexAttribArray(texLoc);
eglSwapBuffers(display, surface);
}
My cameras zoom value is 45.0f and this is the GetViewMatrix method:
glm::mat4 Camera::GetViewMatrix()
{
return glm::lookAt(Position, Position + Front, Up);
}
and finally the shaders:
vert.cg
void main
(
uniform float4x4 mvp,
float4 vPosition,
float2 vTexCoord: TEXCOORD0,
out float4 oPosition: POSITION,
out float2 fTexCoord: TEXCOORD
)
{
oPosition = mul(mvp, vPosition);
fTexCoord = vTexCoord;
};
frag.cg
float4 main
(
in float2 fTexCoord: TEXCOORD0,
uniform sampler2D texture1: TEXUNIT0
)
{
float4 col;
col = tex2D(texture1, fTexCoord);
return col;
}
I have a feeling it has something to do with my projection matrix but I'm not entirely sure. Any help is greatly appreciated, thank you
UPDATE:
If I update the near value in glm::perspective from 0.1f to 1.0f it produces a better looking but still false result, so I'm pretty sure the issue is in my projection matrix. What am I doing wrong here?
projection = glm::perspective(glm::radians(camera.Zoom), aspect, 0.1f, 100.0f);
becomes
projection = glm::perspective(glm::radians(camera.Zoom), aspect, 1.0f, 100.0f);
for the following results:
Wider but still incorrect
Another angle
Again

I've found the issue. I was multiplying the model view projection matrix incorrectly in the vert shader.
oPosition = mul(mvp, vPosition);
should be
oPosition = mul(vPosition, mvp);
this works with a near value of 0.1f
EDIT
Also the missing faces were due to incorrect winding order with my vertices. Here is a corrected set of vertices, they are in clockwise order glFrontFace(GL_CW);
GLfloat vertices[] = {
// Back face
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, // Bottom-left
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, // bottom-right
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, // top-right
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, // top-right
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, // top-left
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, // bottom-left
// Front face
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, // bottom-left
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, // top-right
0.5f, -0.5f, 0.5f, 1.0f, 0.0f, // bottom-right
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, // top-right
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, // bottom-left
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, // top-left
// Left face
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f, // top-right
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f, // bottom-left
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f, // top-left
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f, // bottom-left
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f, // top-right
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, // bottom-right
// Right face
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, // top-left
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, // top-right
0.5f, -0.5f, -0.5f, 0.0f, 1.0f, // bottom-right
0.5f, -0.5f, -0.5f, 0.0f, 1.0f, // bottom-right
0.5f, -0.5f, 0.5f, 0.0f, 0.0f, // bottom-left
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, // top-left
// Bottom face
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f, // top-right
0.5f, -0.5f, 0.5f, 1.0f, 0.0f, // bottom-left
0.5f, -0.5f, -0.5f, 1.0f, 1.0f, // top-left
0.5f, -0.5f, 0.5f, 1.0f, 0.0f, // bottom-left
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f, // top-right
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, // bottom-right
// Top face
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, // top-left
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, // top-right
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, // bottom-right
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, // bottom-right
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f, // bottom-left
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f // top-left
};

How to draw an cube using index buffers? [duplicate]

This question already has answers here:
Rendering meshes with multiple indices
(2 answers)
Why does OpenGL not support multiple index buffering?
(1 answer)
i'm trying to implement index buffer object in opentk but don't know how to actually use it when drawing things
(2 answers)
How do I wrap a sprite around a cube without GL_REPEAT? [closed]
(1 answer)
Closed 2 years ago.
I have the following vertex buffer in my opengl program that gets translated to a different location later on.
float vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};
There are lots of repeated elements in the vertex buffer. How can I use an index buffer to optimize video memory usage?
There are 2 vertex attributes:
- Position (3 floats)
- Texture Coordinates (2 floats)
How can I use an index buffer? And what will be the vertex and index buffer contents?

initializing a static const array inside a class - c++

Consider the following code, I've marked the important line with #this symbol:
#include <glad/include/glad/glad.h>
#include <string>
#include <iostream>
#ifndef LAMP_H
#define LAMP_H
namespace lmp{
class genLamp{
unsigned int lmpVAO;
static const float flag{1}; //#this is allowed
static const float default_shape[]{ //#this is not allowed
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};
genLamp(std::string vShaderPath, std::string fShaderPath){
glGenVertexArrays(1, &lmpVAO);
glBindVertexArray(lmpVAO);
}
unsigned int getVAO(){
return this->lmpVAO;
}
};
}
#endif
First of all, why is this even not allowed, what problem is the language trying to prevent by preventing this? And,
Since the default_shape array is going to be the same across objects no matter what, I was trying to share this array by making it static. But, this doesn't seem to be possible. The only thing I can think of is declaring the variable into a global scope, which is not so good in my case. Does c++ have any syntax to declare and initialize static const arrays ? I'm compiling with c++17 in case the information is useful.
EDIT: if possible please also explain #user's answer

Make them inline. The following code compiles.
class Temp {
inline static const float values[] = { 0.0f, 1.0f };
};
Or even better,
class Temp {
constexpr static float values[] = { 0.0f, 1.0f };
};
Thanks to John for pointing this out.

VAO gets deleted without calling glDeleteVertexArrays()

I have just started to learn OpenGL and I am currently trying to apply the OpenGL knowledge I have acquired in a small game architecture, but I am having a hard time making this work with Classes. I am trying to display a triangle on the screen using a separate class like this:
CubeModel.h
#pragma once
#include <vector>
#include <glad\glad.h>
class CubeModel
{
public:
//x y and z are dimensions of the cube
CubeModel();
CubeModel( float x, float y, float z);
~CubeModel();
void Bind();
void Unbind();
private:
unsigned int m_VAO, m_VBO;
std::vector<float> m_vertices = {
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
0.0f, 0.5f, 0.0f
};
std::vector<float> m_vertices2 = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};
};
CubeModel.cpp
#include "CubeModel.h"
CubeModel::CubeModel()
{
CubeModel(1.0f, 1.0f, 1.0f);
}
CubeModel::CubeModel(float x, float y, float z)
{
unsigned int VAO, VBO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(m_vertices[0]) * m_vertices.size(),
m_vertices.data(), GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glBindVertexArray(0);
m_VAO = VAO;
m_VBO = VBO;
}
CubeModel::~CubeModel()
{
glDeleteVertexArrays(1, &m_VAO);
glDeleteBuffers(1, &m_VBO);
}
void CubeModel::Bind()
{
glBindVertexArray(m_VAO);
}
void CubeModel::Unbind()
{
glBindVertexArray(0);
}
Game_State.h (where CubeModel is used):
#pragma once
#include "Window.h"
#include "Shader.h"
#include "CubeModel.h"
#define TIMESTEP 1.0f/100.0f
class Game_State
{
public:
Game_State();
~Game_State();
int Run();
bool IsDone();
private:
void HandleInput();
void Update(double deltatime);
void Render();
Window m_window;
double m_elapsedTime = 0;
Shader m_cubeShader;
CubeModel m_testCube;
};
Game_State.cpp:
#include "Game_State.h"
Game_State::Game_State()
: m_window("Title to be determined...", glm::vec2(1920, 1080))
, m_cubeShader("cubeshader.vs","cubeshader.fs")
{
}
Game_State::~Game_State()
{
}
int Game_State::Run()
{
while (m_elapsedTime > TIMESTEP)
{
m_elapsedTime -= TIMESTEP;
HandleInput();
Update(m_elapsedTime);
}
Render();
m_elapsedTime += glfwGetTime();
glfwSetTime(0.0f);
return 0;
}
void Game_State::Update(double deltatime)
{
m_window.Update();
}
void Game_State::Render()
{
m_window.BeginDraw(0.7f, 0.5f, 0.3f, 1.0f);
m_cubeShader.use();
m_testCube.Bind();
glDrawArrays(GL_TRIANGLES, 0, 6);
m_testCube.Unbind();
m_window.EndDraw();
}
void Game_State::HandleInput()
{
if (glfwGetKey(m_window.GetWindow(), GLFW_KEY_F11) == GLFW_PRESS)
{
m_window.ToggleFullscreen();
}
if (glfwGetKey(m_window.GetWindow(), GLFW_KEY_ESCAPE) == GLFW_PRESS)
{
m_window.CloseWindow();
}
}
bool Game_State::IsDone() { return m_window.IsDone(); }
When i tried to debug the code, everything was working and the VAO and VBO both got an ID but by the time i call the bind function before drawing it to the screen in a separate render function it binds the array with ID 0. Both the m_VAO and m_VBO gets reset to 0 by the time bind() is called, what is the reason for this?!?! I've tried using this exact code directly in the render function and it works so the render is fine it seems. (I'm using GLFW and GLAD)
Thanks in advance! :)

This:
CubeModel::CubeModel()
{
CubeModel(1.0f, 1.0f, 1.0f);
}
is wrong. That creates a CubeModel temporary within the constructor. That's not the same thing as delegating the constructor. If that's what you wanted, you have to use the proper C++11 syntax:
CubeModel::CubeModel() : CubeModel(1.0f, 1.0f, 1.0f)
{}
Note that this may not be your only problem, since you neglected to post all of your code.
For example, CubeModel is technically copyable, but it shouldn't be. You make no special allowances for copying (which by its nature, would have to create a new VAO and buffer, and copy the data from the other VAO/buffer). So you need to delete the copy operations, and write appropriate move operations:
CubeModel(const CubeModel &) = delete;
CubeModel(CubeModel &&other) : m_VAO(other.m_VAO), m_VBO(other.m_VBO)
{
other.m_VAO = 0;
other.m_VBO = 0;
}
And do something similar for the move assignment operation. Or just leave it as being unassignable.

In C++, you can't call a constructor from inside another constructor as you do here:
CubeModel::CubeModel()
{
CubeModel(1.0f, 1.0f, 1.0f);
}
What is actually happening here is that you create a temporary, unnamed CubeModel which get's deleted when the default constructor is left. That's when your VAO gets deleted.
If you don't want to duplicate the code in both function, you need to write a new method and call that one from both constructors.