My code renders a black screen - opengl

Question

I'm trying to render a simple wire frame cube using JOGL.
However I am presented with a black screen, can anyone with more experience than me tell if I'm doing something wrong?
The shaders compile and throw no errors.
private Mat4 projectionMatrix;
//reference to the uniform MPV matrix in the vertex shader
private int mpvUnif;
//Holds the references to GL objects
private final int[] glPointers = new int[3];
private static final int VBO = 0;
private static final int INDEXBUFFER = 1;
private static final int VAO = 2;
private int shaderProgram;
private FloatBuffer vertexDataBuffer;
private ShortBuffer indexDataBuffer;
private float[] testCube = new float[] {
//Top
-1, 1, 1, //0
1, 1, 1, //1
-1, -1, 1, //2
1, -1, 1, //3
//Bottom
-1, 1, -1, //4
1, 1, -1, //5
-1, -1, -1, //6
1, -1, -1, //7
};
private short[] testCubeIndexes = new short[] {
0,1,2,3,
4,5,6,7,
0,1,4,5,
2,3,6,7,
0,2,4,6,
1,3,5,7
};
public GLController() {
this.vertexDataBuffer = FloatBuffer.wrap(testCube);
this.indexDataBuffer = ShortBuffer.wrap(testCubeIndexes);
}
#Override
public void init(GLAutoDrawable drawable) {
GL3 gl = drawable.getGL().getGL3();
shaderProgram = gl.glCreateProgram();
try {
InitializeVertexBuffer(gl);
InitializeVertexArrayObjects(gl);
initShaders(gl);
} catch (IOException e) {
e.printStackTrace();
}
gl.glPolygonMode(GL3.GL_FRONT_AND_BACK, GL3.GL_LINE);
gl.glFrontFace(GL3.GL_CW);
}
#Override
public void display(GLAutoDrawable drawable) {
GL3 gl = drawable.getGL().getGL3();
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
gl.glClear(GL3.GL_COLOR_BUFFER_BIT);
gl.glUseProgram(shaderProgram);
gl.glBindVertexArray(glPointers[VAO]);
gl.glDrawElements(GL3.GL_QUADS, indexDataBuffer.capacity(), GL3.GL_UNSIGNED_SHORT, 0);
gl.glBindVertexArray(0);
gl.glUseProgram(0);
}
#Override
public void reshape(GLAutoDrawable drawable, int x, int y, int width, int height) {
GL3 gl = drawable.getGL().getGL3();
mpvUnif = gl.glGetUniformLocation(shaderProgram, "MPV");
projectionMatrix = Matrices.perspective(60f, width/height, .1f, 100f);
gl.glUseProgram(shaderProgram);
gl.glUniformMatrix4fv(mpvUnif, 1, GLHelper.glBool(GL3.GL_FALSE), projectionMatrix.getBuffer());
gl.glUseProgram(0);
}
/**
* Called in GLEventListener.init()
* #param gl
*/
private void InitializeVertexBuffer(GL3 gl) {
gl.glGenBuffers(1, glPointers, VBO);
gl.glBindBuffer(GL3.GL_ARRAY_BUFFER, glPointers[VBO]);
gl.glBufferData(GL3.GL_ARRAY_BUFFER, GLHelper.sizeof(vertexDataBuffer), vertexDataBuffer, GL3.GL_STATIC_DRAW);
gl.glBindBuffer(GL3.GL_ARRAY_BUFFER, 0);
gl.glGenBuffers(1, glPointers, INDEXBUFFER);
gl.glBindBuffer(GL3.GL_ELEMENT_ARRAY_BUFFER, glPointers[INDEXBUFFER]);
gl.glBufferData(GL3.GL_ELEMENT_ARRAY_BUFFER, GLHelper.sizeof(indexDataBuffer), indexDataBuffer, GL3.GL_STATIC_DRAW);
gl.glBindBuffer(GL3.GL_ELEMENT_ARRAY_BUFFER, 0);
}
/**
* Called in GLEventListener.init()
* #param gl
*/
private void InitializeVertexArrayObjects(GL3 gl) {
gl.glGenVertexArrays(1, glPointers, VAO);
gl.glBindVertexArray(glPointers[VAO]);
gl.glBindBuffer(GL3.GL_ARRAY_BUFFER, glPointers[VBO]);
gl.glEnableVertexAttribArray(0);
gl.glVertexAttribPointer(0, 3, GL3.GL_FLOAT, GLHelper.glBool(GL3.GL_FALSE), 0, 0);
gl.glBindBuffer(GL3.GL_ELEMENT_ARRAY_BUFFER, glPointers[INDEXBUFFER]);
gl.glBindVertexArray(0);
}
My vertex shader:
#version 330
layout(location = 0) in vec3 vertexPosition_modelspace;
uniform mat4 MVP;
void main()
{
vec4 v = vec4(vertexPosition_modelspace, 1);
gl_Position = MVP * v;
}
This shader does draw something on the screen:
#version 330
layout(location = 0) in vec3 vertexPosition_modelspace;
uniform mat4 MVP;//not used
void main()
{
gl_Position = vec4(vertexPosition_modelspace, 1);
}
My fragment shader:
#version 330
out vec4 outputColor;
void main()
{
outputColor = vec4(1.0, 1.0, 1.0, 1.0);
}

Answer 1

I'm feeling so silly, the main problem was that MVP in the shader was referenced as MPV! Thanks to gouessej for trying to help.