C++ functions of pointers to classes don't work? - c++

Question

I'm trying to generate a terrain using perlin noise, to improve the quality of the terrain, I want to use multiple noises at once. So I have written a class that should to that for me. Here are the hpp and cpp files:
#include "perlinNoise.hpp"
class MultiPerlinNoise: public PerlinNoise {
public:
MultiPerlinNoise();
std::vector<PerlinNoise*> perlinNoises;
float octaveNoise(float x, float y);
};
cpp:
#include "multiPerlinNoise.hpp"
MultiPerlinNoise::MultiPerlinNoise():
PerlinNoise(0) {
}
float MultiPerlinNoise::octaveNoise(float x, float y) {
float sum = 0.0f;
for(int i = 0; i < perlinNoises.size(); i++)
sum += perlinNoises[i]->octaveNoise(x, y);
return sum;
}
The PerlinNoise class is a wrapper around the code for a octave peril noise I found on the internet. It looks like this:
#include "sivPerlinNoise.hpp"
class PerlinNoise {
public:
PerlinNoise(unsigned int seed);
float octaveNoise(float x, float y);
float frequency;
float multiplier;
int octaves;
unsigned int seed;
float offset;
private:
siv::PerlinNoise perlinNoise;
};
cpp:
#include "perlinNoise.hpp"
PerlinNoise::PerlinNoise(unsigned int seed):
perlinNoise(seed), frequency(2.0f), multiplier(1.0f), octaves(1), seed(seed), offset(0.0f) {
}
float PerlinNoise::octaveNoise(float x, float y) {
return perlinNoise.octaveNoise(x / frequency, y / frequency, octaves) * multiplier + offset;
}
Now the problem is, that when I pass a pointer to my noise into my map class, the function always return 0.0f. This is how the constructor of my map class looks like:
Map::Map(PerlinNoise *noise, Shader *shader, const RenderData *data):
noise(noise), shader(shader), data(data), texture("resources/textures/stones.png") {
printf("%f\n", noise->octaveNoise(-(CHUNK_SIZE / 2.0f) + 0.0f, -(CHUNK_SIZE / 2.0f) + 0.0f));
update(glm::vec3(0.0f));
}
When I don't use a pointer to my noise everything is working as it should. How can this be fixed?

Answer 1

You need to declare octaveNoise as virtual, so the method can be overridden by inheriting classes:
class MultiPerlinNoise: public PerlinNoise {
public:
MultiPerlinNoise();
std::vector<PerlinNoise*> perlinNoises;
virtual float octaveNoise(float x, float y);
};