Geometry shader and MVP matrices issues - c++

Question

I'm working with openGL's Geometry Shader, and doing some tests to get the hang of it before I move on to more complex tasks. I wrote some code to transform inputted GL_POINTS into GL_TRIANGLE_STRIPs, and I apply the MVP matrix transformation in the Geometry Shader. While rendering without the MVP matrix produces the correct output, rendering with it produces nothing. Here is the code (hopefully minimal enough):
int main(){
// Create context and window
sf::Context context;
sf::Window window(sf::VideoMode(800, 600), "Voxel Engine");
window.setVerticalSyncEnabled(true);
// Initialize glew
glewExperimental = true;
GLenum err = glewInit();
if (err != GLEW_OK){
std::cout << "glewIniti failed, aborting...\n";
}
// Create VAO
GLuint VertexArrayID;
glGenVertexArrays(1, &VertexArrayID);
glBindVertexArray(VertexArrayID);
glClearColor(0.0f, 0.0f, 0.4f, 0.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
// Vector for verts
std::vector<glm::vec3> vertices;
// Insert a few vertices
for (int i = -5; i < 5; i++){
vertices.push_back(glm::vec3(i*.3, 0.0, 0.0));
}
// View matrix vectors
glm::vec3 eye = glm::vec3(0.0f, 5.0f, 5.0f);
glm::vec3 at = glm::vec3(0.0f, 0.0f, 0.0f);
glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f);
// Create VBO for vertices
GLuint vertexbuffer;
glGenBuffers(1, &vertexbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glBufferData(GL_ARRAY_BUFFER, vertices.size()*sizeof(glm::vec3), &vertices[0], GL_STATIC_DRAW);
// Create MVP matrices
glm::mat4 Projection = glm::perspective(45.0f, 4.0f / 3.0f, 0.1f, 100.0f);
glm::mat4 View = glm::lookAt(eye, at, up);
glm::mat4 Model = glm::mat4(1.0f);
// Load the shaders
GLuint programID = LoadShaders("VertexShader.glsl", "GeometryShader.glsl", "FragmentShader.glsl");
// Get uniform locations
GLuint M = glGetUniformLocation(programID, "M");
GLuint V = glGetUniformLocation(programID, "V");
GLuint P = glGetUniformLocation(programID, "P");
// Main loop
bool running = true;
sf::Event event;
while (running){
while (window.pollEvent(event)){
switch (event.type){
case sf::Event::Closed:
window.close();
return 0;
}
}
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(programID);
glUniformMatrix4fv(M, 1, GL_FALSE, &Model[0][0]);
glUniformMatrix4fv(V, 1, GL_FALSE, &View[0][0]);
glUniformMatrix4fv(P, 1, GL_FALSE, &Projection[0][0]);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glDrawArrays(GL_POINTS, 0, 10);
glDisableVertexAttribArray(0);
window.display();
}
return 0;
}
Vertex Shader:
#version 430 core
layout(location = 0) in vec3 position;
void main(){
gl_Position = vec4(position, 1);
}
Geometry Shader:
#version 430 core
layout (points) in;
uniform mat4 M, V, P;
layout (triangle_strip) out;
layout (max_vertices = 14) out;
void main(void){
// create a vertex for each point on the cube
vec4 v1 = M*V*P*(gl_in[0].gl_Position + vec4(.1, -.1, -.1, 0.0));
vec4 v2 = M*V*P*(gl_in[0].gl_Position + vec4(-.1, -.1, -.1, 0.0));
vec4 v3 = M*V*P*(gl_in[0].gl_Position + vec4(.1, .1, -.1, 0.0));
vec4 v4 = M*V*P*(gl_in[0].gl_Position + vec4(-.1, .1, -.1, 0.0));
vec4 v5 = M*V*P*(gl_in[0].gl_Position + vec4(.1, -.1, .1, 0.0));
vec4 v6 = M*V*P*(gl_in[0].gl_Position + vec4(-.1, -.1, .1, 0.0));
vec4 v7 = M*V*P*(gl_in[0].gl_Position + vec4(-.1, .1, .1, 0.0));
vec4 v8 = M*V*P*(gl_in[0].gl_Position + vec4(.1, .1, .1, 0.0));
gl_Position = v4;
EmitVertex();
gl_Position = v3;
EmitVertex();
gl_Position = v7;
EmitVertex();
gl_Position = v8;
EmitVertex();
gl_Position = v5;
EmitVertex();
gl_Position = v3;
EmitVertex();
gl_Position = v1;
EmitVertex();
gl_Position = v4;
EmitVertex();
gl_Position = v2;
EmitVertex();
gl_Position = v7;
EmitVertex();
gl_Position = v6;
EmitVertex();
gl_Position = v5;
EmitVertex();
gl_Position = v2;
EmitVertex();
gl_Position = v1;
EmitVertex();
EndPrimitive();
}
Fragment Shader:
#version 430 core
out vec4 color;
void main(){
color = vec4(0, 1, 0, 1);
}
I can provide my LoadShaders function if necessary, but I don't think the issue lies there.
So, performance aside, is there anything I'm doing which is blatantly incorrect?