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On Android, I'm trying to get a simple OpenGL ES 2.0 application running, which uses a vertex buffer object, but I failed.
I started with this project:
http://developer.android.com/resources/tutorials/opengl/opengl-es20.html
Everything is nicely explained and works as described. Fine.
I added some code, to do the rendering alternatively with the glDrawElements command instead of glDrawArrays. I succeeded.
Now the next step: I want to use a Vertex Buffer Object to do the same thing.
So I added this:
new vars:
private int[] mVBOid = new int[2]; // 2 ids needed for VBO and index buffer oject private ShortBuffer mIndices; // indices used
added code to create the VBO:
ByteBuffer vbb = ByteBuffer.allocateDirect(
triangleCoords.length * SIZEOF_FLOAT);
vbb.order(ByteOrder.nativeOrder());// use the device hardware's native byte order
mTriangleVB = vbb.asFloatBuffer(); // create a floating point buffer from the ByteBuffer
mTriangleVB.put(triangleCoords); // add the coordinates to the FloatBuffer
mTriangleVB.position(0); // set the buffer to read the first coordinate
ByteBuffer ibb = ByteBuffer.allocateDirect(
indices.length * SIZEOF_SHORT);
ibb.order(ByteOrder.nativeOrder()); // use the device hardware's native byte order
mIndices = ibb.asShortBuffer(); // create a short buffer from the ByteBuffer
mIndices.put(indices); // add the indices to the Buffer
mIndices.position(0); // set the buffer to read the first index
GLES20.glGenBuffers(2, mVBOid, 0);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mVBOid[0]);
GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER,
numComponentsPerVertex * SIZEOF_FLOAT,
mTriangleVB,
GLES20.GL_STATIC_DRAW);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, mVBOid[1]);
GLES20.glBufferData(GLES20.GL_ELEMENT_ARRAY_BUFFER,
mNumIndices * SIZEOF_SHORT,
mIndices,
GLES20.GL_STATIC_DRAW);
added code to draw the geometry:
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mVBOid[0]);
GLES20.glVertexAttribPointer(maPositionHandle, nc, GLES20.GL_FLOAT, false, stride, 0);
GLES20.glEnableVertexAttribArray(maPositionHandle);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, mVBOid[1]);
GLES20.glDrawElements(GLES20.GL_TRIANGLE_FAN, mNumIndices, GLES20.GL_UNSIGNED_SHORT, 0);
Note: As the firstly implemented new functionality to render the geometry using glDrawElements without using VBO is working, I know that the mTriangleVB and mIndices variables are correctly filled with the data needed. Also maPositionHandle and muMVPMatrixHandle are correct. In my code I check for GL errors - none are found
My problem: the VBO technique is not working; nothing is seen on the screen, except of the clear color. In a more complex application I get more problems:
other geometries without using VBOs which were rendered correctly are invisible, when a VBO based geometry is introduced
segmentation faults are reported occasionaly. Trying to get the exact cause I commented out a lot of code, and finally found, that the crash occurs even if the geometry is not rendered at all.
The reason of the crash must be the initialization of the VBO - although the crash occurs not immediately, but some time later.
But I still can't figure out why it is not working.
Here's some more information:
My Environment:
The complete Source for the SimpleOpenGLES20Renderer class.
The code is based on this sample:
http://developer.android.com/resources/tutorials/opengl/opengl-es20.html
package com.hugo.simplegles20;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
import android.util.Log;
public class SimpleOpenGLES20Renderer implements GLSurfaceView.Renderer {
public float mAngle;
static String TAG = "SimpleTest";
final int SIZEOF_FLOAT = Float.SIZE / 8;
final int SIZEOF_SHORT = Short.SIZE / 8;
private int[] mVBOid = new int[2]; // 2 ids needed for VBO and index buffer oject
enum TestType {
USE_ARRAY, // (almost) the original code
USE_ELEMENTS, // rendering, using glDrawElements call
USE_VBO_ELEMENTS // using a vertex buffer object (VBO)
}
private TestType mUsage = TestType.USE_VBO_ELEMENTS;
private boolean mFourComponents = true;
private int mNumIndices = 0;
private FloatBuffer mTriangleVB;
private ShortBuffer mIndices;
private final String vertexShaderCode =
// This matrix member variable provides a hook to manipulate
// the coordinates of the objects that use this vertex shader
"uniform mat4 uMVPMatrix; \n" +
"attribute vec4 vPosition; \n" +
"void main(){ \n" +
// the matrix must be included as a modifier of gl_Position
" gl_Position = uMVPMatrix * vPosition; \n" +
"} \n";
private final String fragmentShaderCode =
"precision mediump float; \n" +
"void main(){ \n" +
" gl_FragColor = vec4 (0.63671875, 0.76953125, 0.22265625, 1.0); \n" +
"} \n";
private int mProgram;
private int maPositionHandle;
private int muMVPMatrixHandle;
private float[] mMVPMatrix = new float[16];
private float[] mMMatrix = new float[16];
private float[] mVMatrix = new float[16];
private float[] mProjMatrix = new float[16];
public static void checkGLError(String msg) {
int e = GLES20.glGetError();
if (e != GLES20.GL_NO_ERROR) {
Log.d(TAG, "GLES20 ERROR: " + msg + " " + e);
Log.d(TAG, errString(e));
}
}
public static String errString(int ec) {
switch (ec) {
case GLES20.GL_NO_ERROR:
return "No error has been recorded.";
case GLES20.GL_INVALID_ENUM:
return "An unacceptable value is specified for an enumerated argument.";
case GLES20.GL_INVALID_VALUE:
return "A numeric argument is out of range.";
case GLES20.GL_INVALID_OPERATION:
return "The specified operation is not allowed in the current state.";
case GLES20.GL_INVALID_FRAMEBUFFER_OPERATION:
return "The command is trying to render to or read from the framebuffer" +
" while the currently bound framebuffer is not framebuffer complete (i.e." +
" the return value from glCheckFramebufferStatus is not" +
" GL_FRAMEBUFFER_COMPLETE).";
case GLES20.GL_OUT_OF_MEMORY:
return "There is not enough memory left to execute the command." +
" The state of the GL is undefined, except for the state" +
" of the error flags, after this error is recorded.";
default :
return "UNKNOW ERROR";
}
}
@Override
public void onSurfaceCreated(GL10 uu, EGLConfig config) {
// Set the background frame color
GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
checkGLError("onSurfaceCreated 1");
initShapes();
Log.d(TAG, "load vertex shader");
int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
Log.d(TAG, "load fragment shader");
int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);
mProgram = GLES20.glCreateProgram(); // create empty OpenGL Program
checkGLError("onSurfaceCreated 2");
GLES20.glAttachShader(mProgram, vertexShader); // add the vertex shader to program
checkGLError("onSurfaceCreated 3");
GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
checkGLError("onSurfaceCreated 4");
GLES20.glLinkProgram(mProgram); // creates OpenGL program executables
checkGLError("onSurfaceCreated 5");
// get handle to the vertex shader's vPosition member
maPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
checkGLError("onSurfaceCreated 6");
muMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
checkGLError("onSurfaceCreated 7");
}
@Override
public void onSurfaceChanged(GL10 unused, int width, int height) {
GLES20.glViewport(0, 0, width, height);
float ratio = (float) width / height;
// this projection matrix is applied to object coordinates
// in the onDrawFrame() method
Matrix.frustumM(mProjMatrix, 0, -ratio, ratio, -1, 1, 3, 7);
Matrix.setLookAtM(mVMatrix, 0, 0, 0, -3, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
}
@Override
public void onDrawFrame(GL10 uu) {
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
checkGLError("onDrawFrame 1");
// Add program to OpenGL environment
GLES20.glUseProgram(mProgram);
checkGLError("onDrawFrame 2");
// Use the mAngle member as the rotation value
Matrix.setRotateM(mMMatrix, 0, mAngle, 0, 0, 1.0f);
// Apply a ModelView Projection transformation
Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, mMMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mMVPMatrix, 0);
checkGLError("onDrawFrame 3");
int nc = mFourComponents ? 4 : 3;
int stride = nc * SIZEOF_FLOAT;
switch (mUsage) {
case USE_ARRAY:
// Prepare the triangle data
GLES20.glVertexAttribPointer(maPositionHandle, nc, GLES20.GL_FLOAT, false, stride, mTriangleVB);
checkGLError("onDrawFrame 4");
GLES20.glEnableVertexAttribArray(maPositionHandle);
checkGLError("onDrawFrame 5");
// Draw the triangle
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_FAN, 0, mNumIndices);
checkGLError("onDrawFrame 6");
break;
case USE_ELEMENTS:
// Prepare the triangle data
GLES20.glVertexAttribPointer(maPositionHandle, nc, GLES20.GL_FLOAT, false, stride, mTriangleVB);
checkGLError("onDrawFrame 7");
GLES20.glEnableVertexAttribArray(maPositionHandle);
checkGLError("onDrawFrame 8");
// Draw the triangle
// int indicesSizeInBytes = SIZEOF_SHORT * mNumIndices;
GLES20.glDrawElements(GLES20.GL_TRIANGLE_FAN, mNumIndices, GLES20.GL_UNSIGNED_SHORT, mIndices);
checkGLError("onDrawFrame 9");
break;
case USE_VBO_ELEMENTS:
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mVBOid[0]);
checkGLError("onDrawFrame 14");
GLES20.glVertexAttribPointer(maPositionHandle, nc, GLES20.GL_FLOAT, false, stride, 0);
checkGLError("onDrawFrame 15");
GLES20.glEnableVertexAttribArray(maPositionHandle);
checkGLError("onDrawFrame 16");
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, mVBOid[1]);
checkGLError("onDrawFrame 17");
GLES20.glDrawElements(GLES20.GL_TRIANGLE_FAN, mNumIndices, GLES20.GL_UNSIGNED_SHORT, 0);
checkGLError("onDrawFrame 18");
break;
}
}
private void initShapes(){
float triangleCoords3[] = {
// X, Y, Z
-0.5f, -0.5f, 0,
-0.5f, 0.5f, 0,
-0.2f, -0.2f, 0,
0.5f, -0.5f, 0
};
float triangleCoords4[] = {
// X, Y, Z, W
-0.5f, -0.5f, 0, 1,
-0.5f, 0.5f, 0, 1,
-0.2f, -0.2f, 0, 1,
0.5f, -0.5f, 0, 1
};
short[] indices = {0,1,2,3};
float[] triangleCoords;
int numComponentsPerVertex;
if (mFourComponents) {
triangleCoords = triangleCoords4;
numComponentsPerVertex = 4;
} else {
triangleCoords = triangleCoords3;
numComponentsPerVertex = 3;
}
mNumIndices = triangleCoords.length / numComponentsPerVertex;
Log.d(TAG, "Components per Vertex: " + numComponentsPerVertex);
Log.d(TAG, "Number of Indices : " + mNumIndices);
switch (mUsage) {
case USE_ARRAY:
{
Log.d(TAG, "using array");
// initialize vertex Buffer for triangle
ByteBuffer vbb = ByteBuffer.allocateDirect(
// (# of coordinate values * 4 bytes per float)
triangleCoords.length * SIZEOF_FLOAT);
vbb.order(ByteOrder.nativeOrder());// use the device hardware's native byte order
mTriangleVB = vbb.asFloatBuffer(); // create a floating point buffer from the ByteBuffer
mTriangleVB.put(triangleCoords); // add the coordinates to the FloatBuffer
mTriangleVB.position(0); // set the buffer to read the first coordinate
break;
}
case USE_ELEMENTS:
{
Log.d(TAG, "using VBO elements");
// initialize vertex Buffer for triangle
ByteBuffer vbb = ByteBuffer.allocateDirect(
// (# of coordinate values * 4 bytes per float)
triangleCoords.length * SIZEOF_FLOAT);
vbb.order(ByteOrder.nativeOrder());// use the device hardware's native byte order
mTriangleVB = vbb.asFloatBuffer(); // create a floating point buffer from the ByteBuffer
mTriangleVB.put(triangleCoords); // add the coordinates to the FloatBuffer
mTriangleVB.position(0); // set the buffer to read the first coordinate
vbb = ByteBuffer.allocateDirect(
// (# of coordinate values * 2 bytes per short)
indices.length * SIZEOF_SHORT);
vbb.order(ByteOrder.nativeOrder()); // use the device hardware's native byte order
mIndices = vbb.asShortBuffer(); // create a short buffer from the ByteBuffer
mIndices.put(indices); // add the indices to the Buffer
mIndices.position(0); // set the buffer to read the first index
break;
}
case USE_VBO_ELEMENTS:
{
Log.d(TAG, "using VBO elements");
ByteBuffer vbb = ByteBuffer.allocateDirect(
// (# of coordinate values * 4 bytes per float)
triangleCoords.length * SIZEOF_FLOAT);
vbb.order(ByteOrder.nativeOrder());// use the device hardware's native byte order
mTriangleVB = vbb.asFloatBuffer(); // create a floating point buffer from the ByteBuffer
mTriangleVB.put(triangleCoords); // add the coordinates to the FloatBuffer
mTriangleVB.position(0); // set the buffer to read the first coordinate
ByteBuffer ibb = ByteBuffer.allocateDirect(
indices.length * SIZEOF_SHORT);
ibb.order(ByteOrder.nativeOrder()); // use the device hardware's native byte order
mIndices = ibb.asShortBuffer(); // create a short buffer from the ByteBuffer
mIndices.put(indices); // add the indices to the Buffer
mIndices.position(0); // set the buffer to read the first index
GLES20.glGenBuffers(2, mVBOid, 0);
checkGLError("initShapes 4");
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mVBOid[0]);
checkGLError("initShapes 5");
GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER,
numComponentsPerVertex * SIZEOF_FLOAT,
mTriangleVB,
GLES20.GL_STATIC_DRAW);
checkGLError("initShapes 6");
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, mVBOid[1]);
checkGLError("initShapes 7");
GLES20.glBufferData(GLES20.GL_ELEMENT_ARRAY_BUFFER,
mNumIndices * SIZEOF_SHORT,
mIndices,
GLES20.GL_STATIC_DRAW);
checkGLError("initShapes 8");
break;
}
}
}
private int loadShader(int type, String shaderCode){
// create a vertex shader type (GLES20.GL_VERTEX_SHADER)
// or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
int shader = GLES20.glCreateShader(type);
checkGLError("loadShader 1");
// add the source code to the shader and compile it
GLES20.glShaderSource(shader, shaderCode);
checkGLError("loadShader 2");
GLES20.glCompileShader(shader);
checkGLError("loadShader 3");
// Get the compilation status.
final int[] compileStatus = new int[1];
GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
checkGLError("loadShader 4");
// If the compilation failed, delete the shader.
if (compileStatus[0] == 0)
{
Log.e(TAG, "Error compiling shader: " + GLES20.glGetShaderInfoLog(shader));
GLES20.glDeleteShader(shader);
checkGLError("loadShader 5");
shader = 0;
}
return shader;
}
}
The crash dump: 12-18 14:59:02.790: I/DEBUG(85): * ** * ** * ** * ** * ** *
12-18 14:59:02.790: I/DEBUG(85): Build fingerprint: 'Huawei/U8510/hwu8510:2.3.3/HuaweiU8510/C169B831:user/ota-rel-keys,release-keys'
12-18 14:59:02.790: I/DEBUG(85): pid: 1638, tid: 1646 >>> com.gles20.step1 <<<
12-18 14:59:02.790: I/DEBUG(85): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 00368000
12-18 14:59:02.790: I/DEBUG(85): r0 44affc80 r1 00367ff0 r2 0004f03c r3 00000000
12-18 14:59:02.790: I/DEBUG(85): r4 00000000 r5 00000000 r6 00000000 r7 00000028
12-18 14:59:02.790: I/DEBUG(85): r8 00000000 r9 00000000 10 00000000 fp 00000000
12-18 14:59:02.790: I/DEBUG(85): ip 00368000 sp 443ef9d0 lr 80e02a08 pc afd0cd7c cpsr 20000010
12-18 14:59:02.790: I/DEBUG(85): d0 c420e36a40000000 d1 3f800000c4a0e36a
12-18 14:59:02.790: I/DEBUG(85): d2 000000003f800000 d3 000000003f800000
12-18 14:59:02.790: I/DEBUG(85): d4 0000000000000000 d5 0000000000000000
12-18 14:59:02.790: I/DEBUG(85): d6 3f80000000000000 d7 3f8000003f800000
12-18 14:59:02.790: I/DEBUG(85): d8 0000000000000000 d9 0000000000000000
12-18 14:59:02.800: I/DEBUG(85): d10 0000000000000000 d11 0000000000000000
12-18 14:59:02.800: I/DEBUG(85): d12 0000000000000000 d13 0000000000000000
12-18 14:59:02.800: I/DEBUG(85): d14 0000000000000000 d15 0000000000000000
12-18 14:59:02.800: I/DEBUG(85): scr 20000010
12-18 14:59:02.860: I/DEBUG(85): #00 pc 0000cd7c /system/lib/libc.so
12-18 14:59:02.860: I/DEBUG(85): #01 pc 00002a04 /system/lib/libgsl.so
12-18 14:59:02.860: I/DEBUG(85): #02 pc 00089de0 /system/lib/egl/libGLESv2_adreno200.so
12-18 14:59:02.860: I/DEBUG(85): #03 pc 00091a4a /system/lib/egl/libGLESv2_adreno200.so
12-18 14:59:02.860: I/DEBUG(85): #04 pc 000612ca /system/lib/egl/libGLESv2_adreno200.so
12-18 14:59:02.860: I/DEBUG(85): #05 pc 0006138a /system/lib/egl/libGLESv2_adreno200.so
12-18 14:59:02.860: I/DEBUG(85): #06 pc 00063d94 /system/lib/egl/libGLESv2_adreno200.so
12-18 14:59:02.860: I/DEBUG(85): #07 pc 000836aa /system/lib/egl/libGLESv2_adreno200.so
12-18 14:59:02.860: I/DEBUG(85): #08 pc 0003fd66 /system/lib/libandroid_runtime.so
12-18 14:59:02.860: I/DEBUG(85): #09 pc 00012174 /system/lib/libdvm.so
12-18 14:59:02.860: I/DEBUG(85): code around pc:
12-18 14:59:02.860: I/DEBUG(85): afd0cd5c e0422003 e2522020 3a000008 e3c1c01f
12-18 14:59:02.860: I/DEBUG(85): afd0cd6c e28cc040 e8b10ff0 f5dcf040 e2522020
12-18 14:59:02.860: I/DEBUG(85): afd0cd7c 849c3020 e8a00ff0 2afffff9 e2822020
12-18 14:59:02.860: I/DEBUG(85): afd0cd8c e312001f 0a00000c e1b0ce02 28b100f0
12-18 14:59:02.860: I/DEBUG(85): afd0cd9c 48b10300 28a000f0 48a00300 e1b0cf02
12-18 14:59:02.860: I/DEBUG(85): code around lr:
12-18 14:59:02.860: I/DEBUG(85): 80e029e8 e5906008 e0831001 e1510006 8a000006
12-18 14:59:02.860: I/DEBUG(85): 80e029f8 e5903000 e1a0100e e0830005 eb000a13
12-18 14:59:02.860: I/DEBUG(85): 80e02a08 e1a00004 e28dd008 e8bd8070 e59f104c
12-18 14:59:02.860: I/DEBUG(85): 80e02a18 e59fe04c e1a02005 e79c0001 e08f100e
12-18 14:59:02.860: I/DEBUG(85): 80e02a28 e58d6000 e28000a8 ebfffef8 e3e00000
12-18 14:59:02.860: I/DEBUG(85): stack:
12-18 14:59:02.860: I/DEBUG(85): 443ef990 0000018c
12-18 14:59:02.860: I/DEBUG(85): 443ef994 811bd8b0
12-18 14:59:02.860: I/DEBUG(85): 443ef998 000000c6
12-18 14:59:02.860: I/DEBUG(85): 443ef99c 443efb68
12-18 14:59:02.860: I/DEBUG(85): 443ef9a0 4360beb4
12-18 14:59:02.860: I/DEBUG(85): 443ef9a4 4360bea0
12-18 14:59:02.860: I/DEBUG(85): 443ef9a8 428da7b4
12-18 14:59:02.870: I/DEBUG(85): 443ef9ac 81089e25 /system/lib/egl/libGLESv2_adreno200.so
12-18 14:59:02.870: I/DEBUG(85): 443ef9b0 001e8cc8
12-18 14:59:02.870: I/DEBUG(85): 443ef9b4 443efa6c
12-18 14:59:02.870: I/DEBUG(85): 443ef9b8 00000001
12-18 14:59:02.870: I/DEBUG(85): 443ef9bc 00000001
12-18 14:59:02.870: I/DEBUG(85): 443ef9c0 0000018c
12-18 14:59:02.870: I/DEBUG(85): 443ef9c4 afd10f08 /system/lib/libc.so
12-18 14:59:02.870: I/DEBUG(85): 443ef9c8 df002777
12-18 14:59:02.870: I/DEBUG(85): 443ef9cc e3a070ad
12-18 14:59:02.870: I/DEBUG(85): #00 443ef9d0 00000000
12-18 14:59:02.870: I/DEBUG(85): 443ef9d4 000a3000
12-18 14:59:02.870: I/DEBUG(85): 443ef9d8 0018b834
12-18 14:59:02.870: I/DEBUG(85): 443ef9dc 443efb68
12-18 14:59:02.870: I/DEBUG(85): 443ef9e0 4360beb4
12-18 14:59:02.870: I/DEBUG(85): 443ef9e4 4360bea0
12-18 14:59:02.870: I/DEBUG(85): 443ef9e8 428da7b4
12-18 14:59:02.870: I/DEBUG(85): 443ef9ec 44aac000
12-18 14:59:02.870: I/DEBUG(85): 443ef9f0 00000000
12-18 14:59:02.870: I/DEBUG(85): 443ef9f4 80e02a08 /system/lib/libgsl.so
12-18 14:59:02.870: I/DEBUG(85): #01 443ef9f8 001e9320
12-18 14:59:02.870: I/DEBUG(85): 443ef9fc 00000001
12-18 14:59:02.870: I/DEBUG(85): 443efa00 001e9320
12-18 14:59:02.870: I/DEBUG(85): 443efa04 00000001
12-18 14:59:02.870: I/DEBUG(85): 443efa08 001e9328
12-18 14:59:02.870: I/DEBUG(85): 443efa0c 81089de3 /system/lib/egl/libGLESv2_adreno200.so
573
Creating a VBO requires 3 steps; Generate a new buffer object with glGenBuffers(). Bind the buffer object with glBindBuffer(). Copy vertex data to the buffer object with glBufferData().
A VBO is a buffer of memory which the gpu can access. That's all it is. A VAO is an object that stores vertex bindings. This means that when you call glVertexAttribPointer and friends to describe your vertex format that format information gets stored into the currently bound VAO.
A vertex buffer object (VBO) is an OpenGL feature that provides methods for uploading vertex data (position, normal vector, color, etc.) to the video device for non-immediate-mode rendering.
A Shader Storage Buffer Object is a Buffer Object that is used to store and retrieve data from within the OpenGL Shading Language. SSBOs are a lot like Uniform Buffer Objects. Shader storage blocks are defined by Interface Block (GLSL)s in almost the same way as uniform blocks.
After another day of investigation I found some the problems with my code:
forgot to unbind used buffers; these calls were missing after filling the buffer with data and after using them for drawing the primitive:
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mArray);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, mIndices);
// fill or draw
// ...
// unbind:
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);
calling glBindAttribLocation must occur at the right time: After compiling the shaders, but BEFORE linking the program
// load and compile shaders ...
mProgramId = loadProgram(vertexShaderSource, fragmentShaderSource);
// Bind the locations
GLES20.glBindAttribLocation(mProgramId, Shader.VERTEX_POS, "position");
GLES20.glBindAttribLocation(mProgramId, Shader.NORMAL_POS, "normal");
// finally link program
GLES20.glLinkProgram(mProgramId);
misinterpretation of the index parameter in the
GLES20.glBindAttribLocation
GLES20.glEnableVertexAttribArray
GLES20.glVertexAttribPointer
calls. A deeper look in the spec helps me out. This seems to be always a good idea.
It might be helpful for others who have some problems with VBO setup and usage to have a simple, but complete OpenGL ES 2.0 app as a starting point, so I will post the code here.
I've modified the app found here: https://code.google.com/p/gdc2011-android-opengl, removed everything but VBO relevant code,
set up some classes to encapsule functionality and succeeded in making a Android / VBO starter kit.
This package is one single file, containing the Activity, some helper classes, a basic shader and a camera class and - most important -
a basic VBO class, which wraps all the functionality to create, use and destroy vertex buffer objects.
The app does:
To use it, simply create a new Android project, create an activity 'GLES20VBOTest' and use the following file.
package com.example.vbo;
/*
Note: these not exist or not work before Android 2.3
GLES20.glVertexAttribPointer
GLES20.glDrawElements
*/
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.app.Activity;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
import android.os.Bundle;
import android.util.Log;
public class GLES20VBOTest extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
GLSurfaceView view = new GLSurfaceView(this);
view.setEGLContextClientVersion(2);
view.setRenderer(new GDC11Renderer());
setContentView(view);
}
}
// Helper class to create some different geometries
class GeoData {
public float[] mVertices;
public short[] mIndices;
private GeoData() {}
static public GeoData halfpipe() {
GeoData creator = new GeoData();
creator.mVertices = createVertices1(44);
creator.mIndices = createIndices1(44);
return creator;
}
static public GeoData circle() {
GeoData creator = new GeoData();
creator.mVertices = createVertices2(32);
creator.mIndices = createIndices2(32);
return creator;
}
static public GeoData grid() {
GeoData creator = new GeoData();
creator.mVertices = createGridVertices(30,30);
creator.mIndices = createGridIndices(30,30);
return creator;
}
static float[] createGridVertices(int m, int n) {
float[] vertices = new float[3*(2*m + 2*n + 4)];
float y = 0.1f;
float S = 2.8f;
for (int i=0; i<=m; i++) {
float x = S*(float) (-0.5 + (1.0*i)/m);
float z = S*0.5f;
vertices[6*i + 0] = x;
vertices[6*i + 1] = y;
vertices[6*i + 2] = z;
vertices[6*i + 3] = x;
vertices[6*i + 4] = y;
vertices[6*i + 5] = -z;
}
int start = 3*(2*m + 2);
// start = 0;
for (int i=0; i<=n; i++) {
float z = S*(float) (-0.5 + (1.0*i)/n);
float x = S*0.5f;
vertices[start + 6*i + 0] = x;
vertices[start + 6*i + 1] = y;
vertices[start + 6*i + 2] = z;
vertices[start + 6*i + 3] = -x;
vertices[start + 6*i + 4] = y;
vertices[start + 6*i + 5] = z;
}
float[] M = new float[16];
Matrix.setIdentityM(M, 0);
Matrix.rotateM(M, 0, 27, 0.76f, -0.9f, 1.5f);
int count = (2*m + 2*n + 4);
Log.d("MKZ", "A: " + count);
Log.d("MKZ", "B: " + vertices.length / 3);
for (int i=0; i<count-1; i++) {
int offset = 3*i;
Log.d("MKZ", "offset: " + offset);
Matrix.multiplyMV(vertices, offset, M, 0, vertices, offset);
}
return vertices;
}
static short[] createGridIndices(int m, int n) {
int N = 2*(m+n+2);
short[] indices = new short[N];
for (int i=0; i<N; i++) {
indices[i] = (short)i;
}
return indices;
}
static float[] createVertices1(int n) {
int NUM_COMPONENTS = 6;
float S = 0.75f;
float X = 1f;
float z0 = 1.3f;
float z1 = 1.1f;
float dx = 2*X / n;
float[] vertices = new float[NUM_COMPONENTS*(n+1)*2];
for (int i=0; i<(n+1); i++) {
int I0 = 2*NUM_COMPONENTS*i;
int I1 = 2*NUM_COMPONENTS*i + NUM_COMPONENTS;
float x = -X + dx*i;
float y = -(float) Math.sqrt(1.0 - x*x);
vertices[I0 + 0] = S*x;
vertices[I0 + 1] = S*y;
vertices[I0 + 2] = S*z0;
vertices[I0 + 3] = x;
vertices[I0 + 4] = y;
vertices[I0 + 5] = 0;
vertices[I1 + 0] = S*x;
vertices[I1 + 1] = S*y;
vertices[I1 + 2] = S*z1;
vertices[I1 + 3] = x;
vertices[I1 + 4] = y;
vertices[I1 + 5] = 0;
}
return vertices;
}
static short[] createIndices1(int n) {
short[] indices = new short[(n+1)*2];
for (short i=0; i<(n+1)*2; i++) {
indices[i] = i;
}
return indices;
}
static float[] createVertices2(int n) {
int NUM_COMPONENTS = 6;
float[] vertices = new float[NUM_COMPONENTS*(n+2)];
final float S = 0.9f;
final float Y = -0.0f;
vertices[0] = 0;
vertices[1] = Y;
vertices[2] = 0;
vertices[3] = 0;
vertices[4] =-1;
vertices[5] = 0;
for (int i=0; i<=n; i++) {
int I = 6 + 6*i;
float a = (float) (0.75*2*Math.PI*i/n);
float x = (float) (S*Math.cos(a));
float z = (float) (S*Math.sin(a));
vertices[I+0] = x;
vertices[I+1] = Y;
vertices[I+2] = z;
vertices[I+3] = 0;
vertices[I+4] =-1;
vertices[I+5] = 0;
}
return vertices;
}
static short[] createIndices2(int n) {
short[] indices = new short[(n+2)];
for (short i=0; i<(n+2); i++) {
indices[i] = i;
}
return indices;
}
}
// all GLES20 calls are made here
class Shader {
// THESE ARE ARBITRARY VALUES, the only constraints are
// - must be different
// - must be less than a maximum value
static final int VERTEX_POS = 3;
static final int NORMAL_POS = 4;
static final int TEX_POS = 5;
static final String TAG = "VBOTest";
private int mProgramId;
private int mViewProjectionLoc;
private int mLightVectorLoc;
private int mColorLoc;
private int mEnableLightLoc;
Shader() {
mProgramId = loadProgram(kVertexShader, kFragmentShader);
GLES20.glBindAttribLocation(mProgramId, Shader.VERTEX_POS, "position");
GLES20.glBindAttribLocation(mProgramId, Shader.NORMAL_POS, "normal");
GLES20.glLinkProgram(mProgramId);
mViewProjectionLoc =
GLES20.glGetUniformLocation(mProgramId, "worldViewProjection");
mLightVectorLoc =
GLES20.glGetUniformLocation(mProgramId, "lightVector");
mColorLoc =
GLES20.glGetUniformLocation(mProgramId, "color");
mEnableLightLoc =
GLES20.glGetUniformLocation(mProgramId, "enableLight");
// Other state.
GLES20.glClearColor(0.7f, 0.7f, 0.7f, 1.0f);
GLES20.glEnable(GLES20.GL_CULL_FACE);
GLES20.glEnable(GLES20.GL_DEPTH_TEST);
}
public void use() {
GLES20.glUseProgram(mProgramId);
}
public void setCamera(float[] viewProjectionMatrix) {
GLES20.glUniformMatrix4fv(mViewProjectionLoc,
1,
false, // transpose isn't supported
viewProjectionMatrix, 0);
}
public void setLight(float[] transformedLightVector) {
GLES20.glUniform3fv(mLightVectorLoc, 1, transformedLightVector, 0);
}
public void setColor(float[] color) {
GLES20.glUniform3fv(mColorLoc, 1, color, 0);
}
public void enableLight(boolean val) {
GLES20.glUniform1i(mEnableLightLoc, val ? 1 : 0);
}
static public void setViewPort(int width, int height) {
GLES20.glViewport(0, 0, width, height);
}
private static String kLogTag = "GDC11";
private static int getShader(String source, int type) {
int shader = GLES20.glCreateShader(type);
if (shader == 0) return 0;
GLES20.glShaderSource(shader, source);
GLES20.glCompileShader(shader);
int[] compiled = { 0 };
GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0) {
Log.e(kLogTag, GLES20.glGetShaderInfoLog(shader));
}
return shader;
}
public static int loadProgram(String vertexShader,
String fragmentShader) {
int vs = getShader(vertexShader, GLES20.GL_VERTEX_SHADER);
int fs = getShader(fragmentShader, GLES20.GL_FRAGMENT_SHADER);
if (vs == 0 || fs == 0) return 0;
int program = GLES20.glCreateProgram();
GLES20.glAttachShader(program, vs);
GLES20.glAttachShader(program, fs);
GLES20.glLinkProgram(program);
int[] linked = { 0 };
GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linked, 0);
if (linked[0] == 0) {
Log.e(kLogTag, GLES20.glGetProgramInfoLog(program));
return 0;
}
return program;
}
private static final String kVertexShader =
"precision mediump float; \n" +
"uniform mat4 worldViewProjection; \n" +
"uniform vec3 lightVector; \n" +
"attribute vec3 position; \n" +
"attribute vec3 normal; \n" +
"varying float light; \n" +
"void main() { \n" +
// |lightVector| is in the model space, so the model
// doesn't have to be transformed.
" light = max(dot(normal, lightVector), 0.0) + 0.2; \n" +
" gl_Position = worldViewProjection * vec4(position, 1.0); \n" +
"}";
private static final String kFragmentShader =
"precision mediump float; \n" +
"uniform sampler2D textureSampler; \n" +
"uniform vec3 color; \n" +
"uniform int enableLight; \n" +
"varying float light; \n" +
"void main() { \n" +
" if (1 == enableLight) { \n" +
" gl_FragColor = light * vec4(color,1); \n" +
" } else { \n" +
" gl_FragColor = vec4(color,1); \n" +
" } \n" +
// " gl_FragColor = light * vec4(0.1,0.7,0.0,1); \n" +
"}";
public void clearView() {
int clearMask = GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT;
GLES20.glClear(clearMask);
}
}
// view matrices
class Camera {
private float mPhi, mZ = 3.5f;
private float[] mProjectionMatrix = new float[16];
private float[] mViewMatrix = new float[16];
private float[] mViewProjectionMatrix = new float[16];
// Updates mViewProjectionMatrix with the current camera position.
public void updateMatrices() {
Matrix.setIdentityM(mViewMatrix, 0);
Matrix.translateM(mViewMatrix, 0, 0, 0, -mZ);
Matrix.rotateM(mViewMatrix, 0, mPhi, 0, 1, 0);
Matrix.rotateM(mViewMatrix, 0, -90, 1, 0, 0);
Matrix.multiplyMM(
mViewProjectionMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0);
}
public float[] viewMatrix() {
return mViewMatrix;
}
public void perspective(int width, int height) {
float aspect = width / (float)height;
perspectiveM(
mProjectionMatrix,
(float)Math.toRadians(45),
aspect, 0.1f, 15.f);
// aspect, 0.5f, 5.f);
updateMatrices();
}
// Like gluPerspective(), but writes the output to a Matrix.
static private void perspectiveM(
float[] m, float angle, float aspect, float near, float far) {
float f = (float)Math.tan(0.5 * (Math.PI - angle));
float range = near - far;
m[0] = f / aspect;
m[1] = 0;
m[2] = 0;
m[3] = 0;
m[4] = 0;
m[5] = f;
m[6] = 0;
m[7] = 0;
m[8] = 0;
m[9] = 0;
m[10] = far / range;
m[11] = -1;
m[12] = 0;
m[13] = 0;
m[14] = near * far / range;
m[15] = 0;
}
public void use(Shader shader) {
shader.setCamera(mViewProjectionMatrix);
}
}
// The renderer object.
// Manages the graphic view / content
class GDC11Renderer implements GLSurfaceView.Renderer {
// OpenGL state stuff.
private Shader mShader;
private Camera mCamera;
VBO mVBO1, mVBO2, mVBO3;
private float[] mLightVector = { 2/3.f, 1/3.f, 2/3.f }; // Needs to be normalized
private float[] mTransformedLightVector = new float[3];
private void updateLightVector() {
// Transform the light vector into model space. Since mViewMatrix
// is orthogonal, the reverse transform can be done by multiplying
// with the transpose.
float[] viewMatrix = mCamera.viewMatrix();
mTransformedLightVector[0] =
viewMatrix[0] * mLightVector[0] +
viewMatrix[1] * mLightVector[1] +
viewMatrix[2] * mLightVector[2];
mTransformedLightVector[1] =
viewMatrix[4] * mLightVector[0] +
viewMatrix[5] * mLightVector[1] +
viewMatrix[6] * mLightVector[2];
mTransformedLightVector[2] =
viewMatrix[8] * mLightVector[0] +
viewMatrix[9] * mLightVector[1] +
viewMatrix[10] * mLightVector[2];
}
// This is called continuously to render.
@Override
public void onDrawFrame(GL10 unused) {
mShader.use();
mShader.clearView();
mCamera.use(mShader);
mShader.setLight(mTransformedLightVector);
// VBO
mShader.enableLight(true);
mShader.setColor(red);
mVBO1.draw();
mShader.setColor(gold);
mVBO2.draw();
mShader.enableLight(false);
mShader.setColor(brown);
mVBO3.draw();
}
static float[] green = {0.2f,1,0.2f};
static float[] brown = {0.7f,0.4f,0.2f};
static float[] red = {0.9f,0,0};
static float[] gold = {0.9f,0.8f,0.1f};
static float[] black = {0,0,0};
@Override
public void onSurfaceCreated(GL10 unused, EGLConfig config) {
// CREATE GEOMETRY
// NEVER load stuff on the render thread in real life!
// You'd call fc.map() and b.load() on a loader thread, and
// only then upload that to GL once it's done.
mShader = new Shader();
mCamera = new Camera();
GeoData data = GeoData.halfpipe();
mVBO1 = new VBO(data.mVertices, data.mIndices, GLES20.GL_TRIANGLE_STRIP, true, false, -1);
data = GeoData.circle();
mVBO2 = new VBO(data.mVertices, data.mIndices, GLES20.GL_TRIANGLE_FAN, true, false, -1);
data = GeoData.grid();
mVBO3 = new VBO(data.mVertices, data.mIndices, GLES20.GL_LINES, false, false, -1);
}
// This is called when the surface changes, e.g. after screen rotation.
@Override
public void onSurfaceChanged(GL10 unused, int width, int height) {
mCamera.perspective(width, height);
updateLightVector();
// Necessary if the manifest contains |android:configChanges="orientation"|.
Shader.setViewPort(width, height);
}
}
class VBO {
int mNumIndices;
int mIndexBufferId;
int mVertexBufferId;
boolean mUseNormals;
boolean mUseTexCoords;
int mType;
int mNumComponents;
int mStride;
VBO(float[] vertices, // array of vertex data
short[] indices, // indices
int type, // GL_POINTS, GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES,
// GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, and GL_TRIANGLES
boolean vertexNormals, // normals used ?
boolean vertexTexCoords, // texCoords used ?
int stride) { // struct size in bytes; if stride <= 0 -> stride will be calculated
mType = type;
mUseNormals = vertexNormals;
mUseTexCoords = vertexTexCoords;
mNumComponents = 3;
if (mUseNormals) {
mNumComponents += 3;
}
if (mUseTexCoords) {
mNumComponents += 2;
}
if (stride <= 0) {
mStride = 4 * mNumComponents;
} else {
mStride = stride;
}
int[] buffers = {0,0};
GLES20.glGenBuffers(2, buffers, 0);
mVertexBufferId = buffers[0];
mIndexBufferId = buffers[1];
createVertexBuffer(GLES20.GL_ARRAY_BUFFER, vertices, mVertexBufferId);
createIndexBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, indices, mIndexBufferId);
mNumIndices = indices.length;
}
void deleteBuffers() {
int[] buffers = {mVertexBufferId, mIndexBufferId};
GLES20.glDeleteBuffers(2, buffers, 0);
mVertexBufferId = 0;
mIndexBufferId = 0;
}
void draw() {
if (0 == mVertexBufferId) {
return;
}
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mVertexBufferId);
GLES20.glEnableVertexAttribArray(Shader.VERTEX_POS);
if (mUseNormals) {
GLES20.glEnableVertexAttribArray(Shader.NORMAL_POS);
}
if (mUseTexCoords) {
GLES20.glEnableVertexAttribArray(Shader.TEX_POS);
}
int offset = 0;
GLES20.glVertexAttribPointer(
Shader.VERTEX_POS, // generic id
3, // vertex has 3 components
GLES20.GL_FLOAT, // data type
false, // no normalizing
mStride, // stride: sizeof(float) * number of components
offset); // offset 0; vertex starts at zero
offset += 4 * 3;
if (mUseNormals) {
GLES20.glVertexAttribPointer(
Shader.NORMAL_POS,
3,
GLES20.GL_FLOAT,
false,
mStride,
offset);
offset += 4 * 3;
}
if (mUseTexCoords) {
GLES20.glVertexAttribPointer(
Shader.TEX_POS,
2, // texCoord has 2 components
GLES20.GL_FLOAT,
false,
mStride,
offset);
offset += 4 * 3;
}
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, mIndexBufferId);
GLES20.glDrawElements(mType, mNumIndices, GLES20.GL_UNSIGNED_SHORT, 0);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);
GLES20.glDisableVertexAttribArray(Shader.VERTEX_POS);
GLES20.glDisableVertexAttribArray(Shader.NORMAL_POS);
GLES20.glDisableVertexAttribArray(Shader.TEX_POS);
}
static void createVertexBuffer(int target, float[] vertices, int bufferId) {
int size = vertices.length * 4;
FloatBuffer fb = ByteBuffer.allocateDirect(4*vertices.length).order(ByteOrder.nativeOrder()).asFloatBuffer();
fb.put(vertices);
fb.position(0);
createBuffer(target, fb, size, bufferId);
}
static void createIndexBuffer(int target, short[] indices, int bufferId) {
int size = indices.length * 2;
ShortBuffer sb = ByteBuffer.allocateDirect(size).order(ByteOrder.nativeOrder()).asShortBuffer();
sb.put(indices);
sb.position(0);
createBuffer(target, sb, size, bufferId);
}
static void createBuffer(int target, Buffer buf, int size, int bufferId) {
GLES20.glBindBuffer(target, bufferId);
GLES20.glBufferData(target, size, buf, GLES20.GL_STATIC_DRAW);
GLES20.glBindBuffer(target, 0);
}
}
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