Generate one inserted object multiple times - c++

Question

I am trying to create 5x5x5 cubes for my game. Right now, I have this code which shows only one cube in the camera view. Obviously, it is "inserted" only one time.
void onIdle() override {
// Animate using time when activated
if (animationEnabled) time = (float) glfwGetTime();
// Set gray background
glClearColor(.5f, .5f, .5f, 0);
// Clear depth and color buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Create object matrices
auto cubeMat = rotate(mat4{}, time, {1.0f, 1.0f, 0.0f});
//auto cubeMat = mat4(1.0f);
auto sphereMat = rotate(mat4{}, (float)time, {0.5f, 1.0f, 0.0f});
cubeMat = scale(cubeMat, {0.2f, 0.2f, 0.2f});
// Camera position/rotation - for example, translate camera a bit backwards (positive value in Z axis), so we can see the objects
auto cameraMat = translate(mat4{}, {0, 0, -4.0f});
program.setUniform("ViewMatrix", cameraMat);
// Update camera position with perspective projection
program.setUniform("ProjectionMatrix", perspective((PI / 180.f) * 60.0f, 1.0f, 0.1f, 10.0f));
program.setUniform("LightDirection", normalize(vec3{1.0f, -1.0f, 1.0f}));
// Render objects
// Central box
program.setUniform("Texture", cubeTexture);
for (int i = 0; i < 5*5*5; ++i)
{
program.setUniform("ModelMatrix", cubeMat[i]);
cube.render();
}
}
};
How can I generate 5x5x5 cubes so I don't have to manually insert them so many times? Also, every insertion should give each cube its specific location to create a big 3D cube full of little 5x5x5 cubes (like rubik's cube) or even better, here is a good example.

Answer 1

You need a function which generates a model matrix for an individual cube:
mat4 CubeMat( int x, int y, int z )
{
mat4 cubeMat;
//cubeMat = rotate(cubeMat, time, {1.0f, 1.0f, 0.0f});
//cubeMat = scale(cubeMat, {0.2f, 0.2f, 0.2f});
cubeMat = translate(cubeMat, {1.5f*(float)x-4.0f, 1.5f*(float)y-4.0f, 1.5f*(float)z-4.0f});
return cubeMat;
}
You have to call cube.render(); 5*5*5 times and you have to set 5*5*5 idividual model matrices:
for (int x = 0; x < 5; ++x)
{
for (int y = 0; y < 5; ++y)
{
for (int z = 0; z < 5; ++z)
{
mat4 cubeMat = CubeMat(x, y, z);
program.setUniform("ModelMatrix", cubeMat);
cube.render();
}
}
}