C++ OpenGL Textured Cube Missing Triangles - c++

Question

On my journey towards being competent at OpenGL, I was trying to make a textured cube when I came upon this problem:
Only part of my cube is being rendered. There should be 12 triangles but only 3 of them are being rendered. I've looked at many tutorials, but I can't seem to find the problem/main difference between our code. Here's mine:
...
int main(int argc, char* argv[]) {
if (!setupGLFW()) return 1;
setupApple();
glfwWindowHint(GLFW_SAMPLES, 4);
GLFWwindow* window = glfwCreateWindow(WIN_WIDTH, WIN_HEIGHT, "Textured Cube", NULL, NULL);
if (!window) {
log_msg(LOG_ERROR, "Could not open a GLFW3 window!\n");
return 1;
}
glfwMakeContextCurrent(window);
if (!setupGLEW()) return 1;
glClearColor(0.5, 0.5, 0.5, 1.0);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
static const int vertices = 12 * 3;
static const GLfloat points[] = {
-1.0, -1.0, -1.0,
-1.0, -1.0, 1.0,
-1.0, 1.0, 1.0,
1.0, 1.0, -1.0,
-1.0, -1.0, -1.0,
-1.0, 1.0, -1.0,
1.0, -1.0, 1.0,
-1.0, -1.0, -1.0,
1.0, -1.0, -1.0,
1.0, 1.0, -1.0,
1.0, -1.0, -1.0,
-1.0, -1.0, -1.0,
-1.0, -1.0, -1.0,
-1.0, 1.0, 1.0,
-1.0, 1.0, -1.0,
1.0, -1.0, 1.0,
-1.0, -1.0, 1.0,
-1.0, -1.0, -1.0,
-1.0, 1.0, 1.0,
-1.0, -1.0, 1.0,
1.0, -1.0, 1.0,
1.0, 1.0, 1.0,
1.0, -1.0, -1.0,
1.0, 1.0, -1.0,
1.0, -1.0, -1.0,
1.0, 1.0, 1.0,
1.0, -1.0, 1.0,
1.0, 1.0, 1.0,
1.0, 1.0, -1.0,
-1.0, 1.0, -1.0,
1.0, 1.0, 1.0,
-1.0, 1.0, -1.0,
-1.0, 1.0, 1.0,
1.0, 1.0, 1.0,
-1.0, 1.0, 1.0,
1.0, -1.0, 1.0
};
static const GLfloat textureCoords[] = {
0, 0,
1, 0,
0, 1,
0, 1,
1, 0,
1, 1,
0, 0,
1, 0,
0, 1,
0, 1,
1, 0,
1, 1,
0, 0,
1, 0,
0, 1,
0, 1,
1, 0,
1, 1,
0, 0,
1, 0,
0, 1,
0, 1,
1, 0,
1, 1,
0, 0,
1, 0,
0, 1,
0, 1,
1, 0,
1, 1,
0, 0,
1, 0,
0, 1,
0, 1,
1, 0,
1, 1,
};
GLuint pointBuffer;
glGenBuffers(1, &pointBuffer);
glBindBuffer(GL_ARRAY_BUFFER, pointBuffer);
glBufferData(GL_ARRAY_BUFFER, vertices * 3, points, GL_STATIC_DRAW);
GLuint textureBuffer;
glGenBuffers(1, &textureBuffer);
glBindBuffer(GL_ARRAY_BUFFER, textureBuffer);
glBufferData(GL_ARRAY_BUFFER, vertices * 2, textureCoords, GL_STATIC_DRAW);
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glBindBuffer(GL_ARRAY_BUFFER, pointBuffer);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
glBindBuffer(GL_ARRAY_BUFFER, textureBuffer);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, NULL);
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
GLuint program = getProgramFromFiles("text_cube.vs.glsl", "text_cube.fs.glsl");
glm::mat4 MVP = calculateMVP();
GLuint texture = loadBMP("uvtemplate.bmp");
if (!program) {
log_msg(LOG_ERROR, "There was a problem opening shader.\n");
// clean up
return 1;
}
if (!texture) {
log_msg(LOG_ERROR, "There was a problem opening shader.\n");
// clean up
return 1;
}
glUseProgram(program);
GLuint MVPID = glGetUniformLocation(program, "MVP");
GLuint textureID = glGetUniformLocation(program, "cube_texture");
glUniformMatrix4fv(MVPID, 1, GL_FALSE, &MVP[0][0]);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
glUniform1i(textureID, 0);
while (!glfwWindowShouldClose(window) && glfwGetKey(window, GLFW_KEY_ESCAPE) != GLFW_PRESS) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, vertices);
glfwPollEvents();
glfwSwapBuffers(window);
}
// clean up
return 0;
}
Just so you know, the error is not with setupGLFW(), setupApple(), setupGLEW(), getProgramFromFiles(), calculateMVP(), loadBMP(), or my vertex and fragment shaders, which are in different files. This compiles fine because I include GLFW and GLEW from myglutils.h This is uvtemplate.bmp, its a 512x512 image:
If you guys could help me, it would be greatly appreciated. Thanks!

Answer 1

The problem is the call to glBufferData(). You set the size in floats but you have to specify it in bytes using sizeof(GLfloat). That's why OpenGL isn't receiving all of your data.
void glBufferData
(
GLenum target,
GLsizeiptr size,
const GLvoid* data,
GLenum usage
);
So you need to replace:
glBufferData(GL_ARRAY_BUFFER, vertices * 3, points, GL_STATIC_DRAW);
glBufferData(GL_ARRAY_BUFFER, vertices * 2, textureCoords, GL_STATIC_DRAW);
with:
glBufferData(GL_ARRAY_BUFFER, vertices * 3 * sizeof(GLfloat), points, GL_STATIC_DRAW);
glBufferData(GL_ARRAY_BUFFER, vertices * 2 * sizeof(GLfloat), textureCoords, GL_STATIC_DRAW);