#Java lwjgl how to resize vao code

We could also use a method for calling GL15.glBufferSubData. The Index VBO doesnвЂ™t matter so much, since we shared it. Plus, since target can vary (even if it doesnвЂ™t for our usage), itвЂ™d be a good idea to provide a VBOвЂ™s target to a Quad when setting its VBO ID. We just have to be careful, because we should always have a particular QuadвЂ™s VAO bound if weвЂ™re using its Vertex VBO. Then unbind from the VBO.ДЄlso, if we want to, we can give the Quad class some methods for binding to their VAO and VBOs.

Offset should be 0, target is the same as our original buffer call ( GL15.GL_ARRAY_BUFFER), and data is of course the QuadвЂ™s float buffer. Then, bind to its Vertex VBO, and call GL15.glBufferSubData(target, offset, data).

#Java lwjgl how to resize vao code

And since it keeps track of when it last buffered the vertices, the bufferVertices() method could return a boolean, indicating whether or not it actually needed to.ДЄt any rate, in our draw method, just after binding to the QuadвЂ™s VAO, we want to buffer the QuadвЂ™s vertices (using the above described method, the following code can be inside an if block). You donвЂ™t have to do this, it just saves on CPU cycles. So, we can make a new field in Quad, to keep track of whether or not the vertices have changed since it last buffered them.

However, we donвЂ™t have to call this every single frame вЂ“ just when the QuadвЂ™s position has changed. This updates the data that OpenGL uses to draw with, which can create the illusion of movement. Now in order to make our Quad move about, what we have to do is bind to the relevant VBO and use another method call: GL15.glBufferSubData(target, offset, data). It should be pretty easy to make the QuadвЂ™s translate method use this method. In Quad, we can make a translate method, which moves all Vertices in a direction, thereby simply moving the Quad about.ДЄnd in our Vertex class, we can make a method to change the coordinates, say for example, addXYZW. However, just calling Keyboard.poll() doesnвЂ™t work вЂ“ you have to call Display.processMessages() at the start of our tick method.ДЄs for changing the quadвЂ™s position, letвЂ™s make some new methods. If we change the quadвЂ™s position just a little bit each frame it is, that creates movement! Just remember, use a small value вЂ“ 0.01 is a nice speed. In that method, we can check for keyboard events quite simply: for example, Keyboard.isKeyDown(Keyboard.KEY_W) to see if the W key is currently pressed. Also add a call to our tick method, before the draw call. ItвЂ™s also a good idea to have two different threads вЂ“ one for input, and one for drawing, but we wonвЂ™t worry about that for now. That stops it from polling input devices. Now, Display.update() automatically polls the keyboard, but weвЂ™ll be polling it ourselves now, so change it to Display.update(false). Holding A, you get a million As), we can set enableRepeatEvents(enable) to false. Because we arenвЂ™t bothered by вЂkey repeatвЂ™ events (e.g. We have to call create() on it, just like Display, making sure to catch and exit on an exception. It will be our tick method.ДЇirst of all, Keyboard is a static class, similar to Display. First of all, letвЂ™s make a new method in our MainClass, which weвЂ™ll call every frame as well. So itвЂ™s totally possible to do something like thisвЂ¦Д«ut uh, letвЂ™s do something a bit moreвЂ¦useful. Draw just means that our application sets it, and OpenGL uses it. Dynamic means weвЂ™ll set it many times and use it many times. Static means вЂ“ We set it once, and use it many times. Although we donвЂ™t strictly need to do this, it gives OpenGL a hint on how to optimize. Instead of giving it GL15.GL_STATIC_DRAW, we want to give it GL15.GL_DYNAMIC_DRAW. Actually, we only have to change one line вЂ“ our glBufferData call in our quad setup method.

If ( !newDims.Now that we have a textured Quad, we can make it move around! It actually wonвЂ™t be that hard to do we just have to change a couple lines of OpenGL, add some convenience methods to our class, and use the LWJGLвЂ™s Keyboard class.ДЇirst the OpenGL. Vector2i newDims = new Vector2i((int)getWidth(),(int)getHeight())