Android using float[] as vertices causes OpenGL error 0x502

Question

I am trying to use an array of floats for my verticies in OpenGLES 2.0 on Android instead of a FloatBuffer but When I do I glDrawArrays gives the error 0x502 or GL_INVALID_OPERATION.

I do not get this error and everything works fine when I use FloatBuffers.

I have read that this error is normally caused by a program not being set. I only use one shader program and I set it when everything initialized.

Here is my code

public class LineEngine {
    private static final float[] IDENTIY = new float[16];
    private float[] mLinePoints;
    private float[] mLineColors;
    private int mCount;

    public LineEngine(int maxLines) {
        Matrix.setIdentityM(IDENTIY, 0);

        mLinePoints = new float[maxLines * 2 * 4];
        mLineColors = new float[maxLines * 2 * 4];

        reset();
    }

    public void addLine(float[] position, float[] color) {
        int offset = mCount * 2 * 4;
        System.arraycopy(position, 0, mLinePoints, offset, 8);
        System.arraycopy(color, 0, mLineColors, offset, 4);
        System.arraycopy(color, 0, mLineColors, offset + 4, 4);

        mCount++;
    }

    public void reset() {
        mCount = 0;
    }

    public void draw() {
        if (mCount > 0) {
            GraphicsEngine.setMMatrix(IDENTIY);
            GraphicsEngine.setColors(mLineColors);
            GraphicsEngine.setVertices4d(mLinePoints);
            GraphicsEngine.disableTexture();
            GLES20.glDrawArrays(GLES20.GL_LINES, 0, mCount * 2);

            int error = GLES20.glGetError();
            if (error != 0)
                Log.e("OpenGL", "Draw " + error); // Prints error 1282

            GraphicsEngine.disableColors();
            reset();
        }
    }
}

This code works fine with no errors

public class LineEngine {
    private static final float[] IDENTIY = new float[16];
    private FloatBuffer mLinePoints;
    private FloatBuffer mLineColors;
    private int mCount;

    public LineEngine(int maxLines) {
        Matrix.setIdentityM(IDENTIY, 0);

        ByteBuffer byteBuf = ByteBuffer.allocateDirect(maxLines * 2 * 4 * 4);
        byteBuf.order(ByteOrder.nativeOrder());
        mLinePoints = byteBuf.asFloatBuffer();

        byteBuf = ByteBuffer.allocateDirect(maxLines * 2 * 4 * 4);
        byteBuf.order(ByteOrder.nativeOrder());
        mLineColors = byteBuf.asFloatBuffer();

        reset();
    }

    public void addLine(float[] position, float[] color) {
        mLinePoints.put(position, 0, 8);
        mLineColors.put(color, 0, 4);
        mLineColors.put(color, 0, 4);
        mCount++;
    }

    public void reset() {
        mLinePoints.position(0);
        mLineColors.position(0);
        mCount = 0;
    }

    public void draw() {
        if (mCount > 0) {
            mLinePoints.position(0);
            mLineColors.position(0);
            GraphicsEngine.setMMatrix(IDENTIY);
            GraphicsEngine.setColors(mLineColors);
            GraphicsEngine.setVertices4d(mLinePoints);
            GraphicsEngine.disableTexture();
            GLES20.glDrawArrays(GLES20.GL_LINES, 0, mCount * 2);

            int error = GLES20.glGetError();
            if (error != 0)
                Log.e("OpenGL", "Draw " + error); // no errors

            GraphicsEngine.disableColors();
            reset();
        }
    }
}

The related GraphicsEngine code is here

public static void setVertices4d(FloatBuffer vertices) {
    GLES20.glVertexAttribPointer(aVertexHandle, 4, GLES20.GL_FLOAT, false,
            16, vertices);
    GLES20.glEnableVertexAttribArray(aVertexHandle);
    mState.shape = -1;
}

public static void setVertices4d(float[] vertices) {
    GLES20.glVertexAttrib4fv(aVertexHandle, vertices, 0);
    GLES20.glEnableVertexAttribArray(aVertexHandle);
    mState.shape = -1;
}

public static void setColors(FloatBuffer colors){
    GLES20.glVertexAttribPointer(aColor, 4, GLES20.GL_FLOAT, false,
            16, colors);
    GLES20.glEnableVertexAttribArray(aColor);
    GLES20.glUniform1i(GraphicsEngine.uEnableColors, 1);
}

public static void setColors(float[] colors){
    GLES20.glVertexAttrib4fv(aColor, colors, 0);
    GLES20.glEnableVertexAttribArray(aColor);
    GLES20.glUniform1i(GraphicsEngine.uEnableColors, 1);
}

I don't want to use FloatBuffers because they are slower to change than an array of floats.

Answer 1

You don't have a choice but to use FloatBuffers for this code.

Your setVertices4d method which takes a float[] is broken, you cannot use glVertexAttrib4fv in that way. glVertexAttrib4 only specifies a single vertex, and using the v version just passes the values of an attribute as an array to that single vertex, it doesn't set up a vertex array similar to the pointer functions.