I recently decided to start Learning OpenGL and got myself a book about OpenGL Core 3.3. The book is generally about C++.
So, after looking for a bit, I found a library in a language I was better in which provided almost the same functionality: lwjgl.
I followed the book's steps and translated the C++ syntax into java syntax, which worked until it got to actually drawing something.
There, the JVM just kept crashing, no matter what I changed about the code. After doing some debugging, I found out that the JVM crashed when I called either glVertexAttribPointer or glDrawArrays.
I am very new to OpenGL, and I am assuming this question must sound very stupid to someone more experienced, but: What do I need to change about this code?
float[] vertices = {
-0.5f, -0.5f, -0.0f,
0.5f, 0.5f, 0.0f,
0.0f,0.5f,0.0f
};
FloatBuffer b = BufferUtils.createFloatBuffer(9);
b.put(vertices);
int VBO = glGenBuffers();
int VAO = glGenVertexArrays();
log.info("VBO:" + VBO + "VAO: " + VAO);
// bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s).
glBindVertexArray(VAO);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 12, 0);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, vertices, GL_STATIC_DRAW);
glBindVertexArray(0);
// Run the rendering loop until the user has attempted to close
// the window or has pressed the ESCAPE key.
while (!glfwWindowShouldClose(window))
{
// input
// -----
// render
// ------
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// draw our first triangle
glUseProgram(shaderProgram);
glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized
glDrawArrays(GL_TRIANGLES, 0, 3);
glBindVertexArray(0); // no need to unbind it every time
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
}
I would be very thankful for any help i can get, if you need more info/ need to see more of my code please let me know. Thanks in advance
You have to bind the vertex buffer object to the target GL_ARRAY_BUFFER, before specifying the vertex attribute:
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 12, 0);
When glVertexAttribPointer is called, the buffer object currently bound to the ARRAY_BUFFER target is associated to the attribute (index) and a reference to the buffer object is stored in the state vector of the Vertex Array Object.