[Solved] Out of memory : glDrawElements

[Rpahut]

Okay, seems like I cannot figure it out myself.

I'm (unsuccessfuly) trying to use VBO's to display bunch of points.

First I was trying to follow this article and all I got was clear black screen. Then I decided to try lwjgl_debug library and it rewarded me with Out of memory exception on call to glDrawRangeElements.

So I've found this source and tried different approach, again with the same result - blank screen with the normal library, Out of memory at glDrawElements with debug library.

As I see it, 49152 bytes of vertex data is not quite enough to run out of memory, so I believe I'm just doing something wrong. I'm not sure I completely understand how buffer objects and buffers related to each other, and thus where problem can be. Any help is appreciated.

Here goes the code:

   // after GL init

    // create and store VBO id for vertex buffer
    IntBuffer ib = BufferUtils.createIntBuffer(1);
    ARBVertexBufferObject.glGenBuffersARB(ib);
    coordsVBOID = ib.get(0);

    // create and store VBO id for index buffer
    ib = BufferUtils.createIntBuffer(1);
    ARBVertexBufferObject.glGenBuffersARB(ib);
    indexVBOID = ib.get(0);

    // gen vertex data
    FvertexBuffer = BufferUtils.createFloatBuffer(16*16*16*3);
    for (int by = 0; by < 16; by++) {
       for (int bx = 0; bx < 16; bx++) {
           for (int bz = 0; bz < 16; bz++) {
               FvertexBuffer.put(2.f * bx);
               FvertexBuffer.put(2.f * by);
               FvertexBuffer.put(2.f * bz);
          }
       }
    }

    // send vertex data to VRAM
    ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB, coordsVBOID);
    ARBVertexBufferObject.glBufferDataARB(ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB, FvertexBuffer, ARBVertexBufferObject.GL_STATIC_DRAW_ARB);

    // gen index data
    IindexBuffer = BufferUtils.createIntBuffer(16*16*16);
    for (int i = 0; i < 16*16*16; i++) {
       IindexBuffer.put(i);
    }

    // send index data to VRAM
    ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ELEMENT_ARRAY_BUFFER_ARB, coordsVBOID);
    ARBVertexBufferObject.glBufferDataARB(ARBVertexBufferObject.GL_ELEMENT_ARRAY_BUFFER_ARB, IindexBuffer, ARBVertexBufferObject.GL_STATIC_DRAW_ARB);

   // render

    GL11.glEnableClientState(GL11.GL_VERTEX_ARRAY);
    ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB, coordsVBOID);
    GL11.glVertexPointer(3, GL11.GL_FLOAT, 0, 0);

    ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ELEMENT_ARRAY_BUFFER_ARB, indexVBOID);
    GL12.glDrawRangeElements(GL11.GL_POINTS, 0, 16*16*16, 16*16*16, GL11.GL_UNSIGNED_INT, 0); // Out of memory

    ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB, 0);
    GL11.glDisableClientState(GL11.GL_VERTEX_ARRAY);

Thanks.

[Rpahut]

Oh, I've finally got it to work. I feel almost as accomplished as Alexander Makeonian when he conquered Babylon.

I still have no idea where I was wrong before. Looks like index data upload before rendering is the missing part 

Here is the working code:

import java.nio.FloatBuffer;
import java.nio.IntBuffer;
import org.lwjgl.BufferUtils;
import org.lwjgl.opengl.ARBVertexBufferObject;


public class VBOUtils {

    static int CreateVBOID() {
        IntBuffer buf = BufferUtils.createIntBuffer(1);
        ARBVertexBufferObject.glGenBuffersARB(buf);
        return buf.get(0);
    }

    static void DeleteVBOID(int vboID) {
        ARBVertexBufferObject.glDeleteBuffersARB(vboID);
    }

    static void SetBufferData(int vboID, FloatBuffer fbuf) {
        ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB, vboID);
        ARBVertexBufferObject.glBufferDataARB(ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB, fbuf, ARBVertexBufferObject.GL_STATIC_DRAW_ARB);
    }

    static void SetBufferData(int vboID, IntBuffer ibuf) {
        ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ELEMENT_ARRAY_BUFFER_ARB, vboID);
        ARBVertexBufferObject.glBufferDataARB(ARBVertexBufferObject.GL_ELEMENT_ARRAY_BUFFER_ARB, ibuf, ARBVertexBufferObject.GL_STATIC_DRAW_ARB);
    }

    static int GetDataSize(int vboID, int target) {
        ARBVertexBufferObject.glBindBufferARB(target, vboID);
        return ARBVertexBufferObject.glGetBufferParameterARB(target, ARBVertexBufferObject.GL_BUFFER_SIZE_ARB);
    }

    static void Unbind(int target) {
        ARBVertexBufferObject.glBindBufferARB(target, 0);
    }
}

        // initialisation

        // create and store VBO id's for buffers
        coordsVBOID = VBOUtils.CreateVBOID();
        indexVBOID = VBOUtils.CreateVBOID();

        // gen vertex data
        FvertexBuffer = BufferUtils.createFloatBuffer(16 * 16 * 16 * 3);
        for (int by = 0; by < 16; by++) {
            for (int bx = 0; bx < 16; bx++) {
                for (int bz = 0; bz < 16; bz++) {
                    FvertexBuffer.put(2.f * bx);
                    FvertexBuffer.put(2.f * by);
                    FvertexBuffer.put(2.f * bz);
                }
            }
        }
        FvertexBuffer.flip();

        // send vertex data to VRAM
        VBOUtils.SetBufferData(coordsVBOID, FvertexBuffer);
        int dataSize = VBOUtils.GetDataSize(coordsVBOID, ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB);
        System.out.println("Vertex data size:");
        System.out.println(dataSize);

        // gen index data
        IindexBuffer = BufferUtils.createIntBuffer(16 * 16 * 16);
        for (int i = 0; i < 16 * 16 * 16; i++) {
            IindexBuffer.put(i);
        }
        IindexBuffer.flip();

        // send index data to VRAM
        VBOUtils.SetBufferData(indexVBOID, IindexBuffer);
        ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ELEMENT_ARRAY_BUFFER_ARB, indexVBOID);
        dataSize = VBOUtils.GetDataSize(ARBVertexBufferObject.GL_ELEMENT_ARRAY_BUFFER_ARB, indexVBOID);
        System.out.println("Index data size:");
        System.out.println(dataSize);

        // rendering

        ARBVertexBufferObject.glBindBufferARB(ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB, coordsVBOID);

        // map - edit data - unmap here
        //ARBVertexBufferObject.glMapBufferARB(...);

        glVertexPointer(3, GL_FLOAT, 0, 0);
        VBOUtils.SetBufferData(indexVBOID, IindexBuffer);

        glEnableClientState(GL_VERTEX_ARRAY);
        glDrawElements(GL_POINTS, 16*16*16, GL_UNSIGNED_INT, 0);

        VBOUtils.Unbind(ARBVertexBufferObject.GL_ARRAY_BUFFER_ARB);
        VBOUtils.Unbind(ARBVertexBufferObject.GL_ELEMENT_ARRAY_BUFFER_ARB);