JOGL 2D Texture Example

OpenGL Development JOGL Development
#1

I’m sorry, but I’ve been trying to find an example of how to do 2D textures with JOGL and just keep failing. My code looks like this:


In reshape:
        gl.glViewport(0, 0, width, height); // Reset The Current Viewport
        gl.glMatrixMode(GL2.GL_PROJECTION); // Select The Projection Matrix
        gl.glLoadIdentity(); // Reset The Projection Matrix
        // hard coded values - this needs to change based on screen size
        gl.glOrthof(0, GL_WIDTH, GL_HEIGHT, 0, -1, 1);
        gl.glMatrixMode(GL2.GL_MODELVIEW); // Select The Modelview Matrix
        gl.glLoadIdentity(); // Reset The Modelview Matrix

In draw:
        gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        gl.glClear(GL2.GL_DEPTH_BUFFER_BIT | GL2.GL_COLOR_BUFFER_BIT);

        gl.glEnable(GL2.GL_TEXTURE_2D);
        gl.glEnable(GL2.GL_BLEND);
        gl.glBlendFunc(GL2.GL_ONE, GL2.GL_ONE_MINUS_SRC_ALPHA);
        gl.glEnableClientState(GL2.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL2.GL_COLOR_ARRAY);
        gl.glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
        gl.glLoadIdentity();

            final Texture mTest = TextureIO.newTexture(getClass().getResource("/images/glass.png"), false, TextureIO.PNG);
            final float[] coordData = {
                    0, 0, //
                    0, 1, //
                    1, 0, //
                    1, 1,
            };
            final float[] vertices = {
                    0.0f, 0.0f, 0, // Left Bottom
                    0.0f, 128, 0, // Left Top
                    128, 0.0f, 0, // Right Bottom
                    128, 128, 0
            };
            // Setup the vertices into the buffer
            verts = Buffers.newDirectFloatBuffer(vertices.length);
            verts.put(vertices).position(0);

            // Setup the texture coordinates
            coords = Buffers.newDirectFloatBuffer(coordData.length);
            coords.put(coordData).position(0);

            mTest.enable(gl);
            mTest.bind(gl);
            gl.glLoadIdentity();
            gl.glTranslatef(100, 100, 0);
            gl.glVertexPointer(3, GL2.GL_FLOAT, 0, verts);
            gl.glTexCoordPointer(2, GL2.GL_FLOAT, 0, coords);
            gl.glDrawArrays(GL2.GL_TRIANGLE_STRIP, 0, 4);

I get a “Invalid memory access of location 0x0 rip=0x11cfae8ae” when it executes gl.glDrawArrays, and I just don’t understand what I’m doing wrong.

I’m almost positive I have the latest version, as I donwloaded from http://jogamp.org/ just the other day.

Any help would be greatly appreciated.

Thank you.

#2

gl.glEnableClientState(gl.GL_VERTEX_ARRAY);
gl.glEnableClientState(gl.GL_TEX_COORD_ARRAY);

Also remember to disable them afterwards.

#3

Sorry, I missed some of the initialization steps in the copy+paste.

That’s how I’ve setup the surface.

#4

Then the crash might be because you don’t disable them later.

#5

When do I have to disable them? Before glDrawArrays? Because if I don’t call glDrawArrays, it doesn’t crash, but, of course, nothing is displayed. If I call glDrawArrays, it crashes, but it feels… like calling disable before drawing wouldn’t work?

#6

Agh, silly me.

gl.glVertexPointer(3, GL2.GL_FLOAT, 0, verts);

Where are your 3D coordinates, mate? It reads outside the bounds of the vertex array since it assumes that it has 3 coordinates per vertex, not 2. Change the 3 to 2 and it should work.

#7

Updated, but still the same problem.

Since it’s saying it’s accessing memory address 0x0, I don’t think the bounds problem would be it? It’s like it’s not even getting the buffers in the first place.

#8

Hi

There are several wrong things in your code. You should not recreate the direct NIO buffers at each draw.

Edit.: There is an example here:

Edit2.: theagentd is right, you have to call gl.glEnableClientState(GL2.GL_TEX_COORD_ARRAY); but don’t call gl.glEnableClientState(GL2.GL_COLOR_ARRAY); as you don’t provide colors in your vertex arrays, the main problem come from that line.

Edit3.: Rather post on the official JogAmp forum, you will probably get more replies.