I've been trying to make a Snake in c++ with Opengl, the main components work and quite everything is fine, but somehow when the Snake's tail gets bigger, it glitches.
Program's exact behaviour:
Basically, I already "made" this but without batch rendering, and this problem didn't appear at all and now i'm just confused about what's happening
EDIT : The glitch only appears after taking when tail's size is an even number
Code:
App.cpp (Where the problem most likely is)
#include <glm/glm.h>
#include <glad/glad.h>
#include <glfw/glfw3.h>
int main(){
// Snake Head
// n_Height is 770 and n_Width is 1090
glm::mat4 proj = glm::ortho(0.0f, float(n_Height), 0.0f, float(n_Height), -1.0f, 1.0f);
Snake::snakeTail = {
n_Width / 2 - 5, n_Height / 2 - 5, 0.0f,
n_Width / 2 - 5, n_Height / 2 + 5, 0.0f,
n_Width / 2 + 5, n_Height / 2 + 5, 0.0f,
n_Width / 2 + 5, n_Height / 2 - 5, 0.0f
};
/*
Each snake tail parts is 12 vertices
*/
// Snake tail
for (int i = 1; i < Snake::tailSize+1; i++) {
Snake::snakeTail.push_back(Snake::snakeTail[0] - i * 10);
Snake::snakeTail.push_back(Snake::snakeTail[1]);
Snake::snakeTail.push_back(0.0f);
Snake::snakeTail.push_back(Snake::snakeTail[3] - i * 10);
Snake::snakeTail.push_back(Snake::snakeTail[4]);
Snake::snakeTail.push_back(0.0f);
Snake::snakeTail.push_back(Snake::snakeTail[6] - i * 10);
Snake::snakeTail.push_back(Snake::snakeTail[7]);
Snake::snakeTail.push_back(0.0f);
Snake::snakeTail.push_back(Snake::snakeTail[9] - i * 10);
Snake::snakeTail.push_back(Snake::snakeTail[10]);
Snake::snakeTail.push_back(0.0f);
}
for (int i = 0; i < n_Height/10*n_Width/10; i++) {
Snake::indices.push_back(i * 4);
Snake::indices.push_back(i * 4 + 1);
Snake::indices.push_back(i * 4 + 2);
Snake::indices.push_back(i * 4 + 2);
Snake::indices.push_back(i * 4 + 3);
Snake::indices.push_back(i * 4);
}
}
//Creates vertex array, index buffer, shader program, vertex buffer and renders
// sets uniform mat4 with proj matrix
Snake.cpp (What happens on collision with apple and when snake moves):
// When snake hits apple
tailSize++;
Snake::snakeTail.push_back(Snake::snakeTail[0] - tailSize * 10);
Snake::snakeTail.push_back(Snake::snakeTail[1]);
Snake::snakeTail.push_back(0.0f);
Snake::snakeTail.push_back(Snake::snakeTail[3] - tailSize * 10);
Snake::snakeTail.push_back(Snake::snakeTail[4]);
Snake::snakeTail.push_back(0.0f);
Snake::snakeTail.push_back(Snake::snakeTail[6] - tailSize * 10);
Snake::snakeTail.push_back(Snake::snakeTail[7]);
Snake::snakeTail.push_back(0.0f);
Snake::snakeTail.push_back(Snake::snakeTail[9] - tailSize * 10);
Snake::snakeTail.push_back(Snake::snakeTail[10]);
Snake::snakeTail.push_back(0.0f);
// On render
for (int i = tailSize; i > 0; i--) {
snakeTail[i * 12] = snakeTail[(i - 1) * 12];
snakeTail[i * 12 + 1] = snakeTail[(i - 1) * 12 + 1];
snakeTail[i * 12 + 3] = snakeTail[(i - 1) * 12 + 3];
snakeTail[i * 12 + 4] = snakeTail[(i - 1) * 12 + 4];
snakeTail[i * 12 + 6] = snakeTail[(i - 1) * 12 + 6];
snakeTail[i * 12 + 7] = snakeTail[(i - 1) * 12 + 7];
snakeTail[i * 12 + 9] = snakeTail[(i - 1) * 12 + 9];
snakeTail[i * 12 + 10] = snakeTail[(i - 1) * 12 + 10];
}
// Movement
snakeTail[0] += addX;
snakeTail[1] += addY;
snakeTail[3] += addX;
snakeTail[4] += addY;
snakeTail[6] += addX;
snakeTail[7] += addY;
snakeTail[9] += addX;
snakeTail[10] += addY;
// Sets buffer data to the new array
glBufferData(&Snake::snakeTail[0], snakeTail.size());
}
So hi, basically the answer was that I did an error that took me hours to find, it was such a simple error and yet it made opengl all act wrong,
I was setting up the buffer by using this :
glBufferData(GL_ARRAY_BUFFER, size, data, GL_STATIC_DRAW);
while I had to do this :
glBufferDara(GL_ARRAY_BUFFER, size*sizeof(float), data, GL_STATIC_DRAW);
so yeh that question was useless, sorry for disturbing everything :3
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