I have been trying to draw a plane with a texture on it, using OpenGL2.0 ES on android. However, I keep getting a logcat error saying "glDrawElements: no data bound to the command - ignoring" (tag: emuglGLESv2_enc) and the plane does not show up anymore.
My plane:
public class Wall {
private FloatBuffer data;
private ShortBuffer indices;
private final int program;
private final int positionHandle;
private final int textureHandle;
private final int samplerHandle;
private final int mvpHandle;
private final int[] buffers = new int[2];
private final int[] textures = new int[1];
private final float[] mvpMatrix = new float[16];
public Wall(String v, String f, Bitmap b) { //vertex shader, fragment shader and texture
data = ByteBuffer.allocateDirect(80).order(ByteOrder.nativeOrder()).asFloatBuffer();
data.put(new float[]{-20.0f, .0f, -20.0f, .0f, .0f, //x, y, z, texCoord x, texCoord y
-20.0f, .0f, 20.0f, .0f, 1.0f,
20.0f, .0f, -20.0f, 1.0f, .0f,
20.0f, .0f, 20.0f, 1.0f, 1.0f});
data.position(0);
indices = ByteBuffer.allocateDirect(8).order(ByteOrder.nativeOrder()).asShortBuffer();
indices.put(new short[]{0, 1, 2, 3});
indices.position(0);
program = GLES20.glCreateProgram();
GLES20.glAttachShader(program, OwnRenderer.getShader(GLES20.GL_VERTEX_SHADER, v)); //compile the shader
GLES20.glAttachShader(program, OwnRenderer.getShader(GLES20.GL_FRAGMENT_SHADER, f));
GLES20.glLinkProgram(program);
positionHandle = GLES20.glGetAttribLocation(program, "inPosition");
textureHandle = GLES20.glGetAttribLocation(program, "inTexture");
samplerHandle = GLES20.glGetUniformLocation(program, "tex");
mvpHandle = GLES20.glGetUniformLocation(program, "mvpMatrix");
GLES20.glGenBuffers(2, buffers, 0);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, buffers[0]);
GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, 80, data, GLES20.GL_STATIC_DRAW);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, buffers[1]);
GLES20.glBufferData(GLES20.GL_ELEMENT_ARRAY_BUFFER, 8, indices, GLES20.GL_STATIC_DRAW);
GLES20.glGenTextures(1, textures, 0);
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textures[0]);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_REPEAT);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_REPEAT);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, b, 0);
b.recycle();
setMVP();
}
public void draw() {
GLES20.glUseProgram(program);
GLES20.glUniform1i(samplerHandle, 0);
GLES20.glUniformMatrix4fv(mvpHandle, 1, false, mvpMatrix, 0);
GLES20.glEnableVertexAttribArray(positionHandle);
GLES20.glVertexAttribPointer(positionHandle, 3, GLES20.GL_FLOAT, false, 20, 0);
GLES20.glEnableVertexAttribArray(textureHandle);
GLES20.glVertexAttribPointer(textureHandle, 2, GLES20.GL_FLOAT, false, 20, 12);
GLES20.glDrawElements(GLES20.GL_TRIANGLE_STRIP, 4, GLES20.GL_UNSIGNED_SHORT, 0);
GLES20.glDisableVertexAttribArray(positionHandle);
GLES20.glDisableVertexAttribArray(textureHandle);
}
private void setMVP() {
//First scaling, then rotation, then translation.
Matrix.setIdentityM(mvpMatrix, 0);
Matrix.multiplyMM(mvpMatrix, 0, MainActivity.viewMatrix, 0, mvpMatrix, 0);
Matrix.multiplyMM(mvpMatrix, 0, MainActivity.projectionMatrix, 0, mvpMatrix, 0);
}
}
Vertex shader:
uniform mat4 mvpMatrix;
attribute vec4 inPosition;
attribute vec2 inTexture;
varying vec2 outTexture;
void main() {
gl_Position = mvpMatrix * inPosition;
outTexture = inTexture;
}
Fragment shader:
precision mediump float;
uniform Sampler2D tex;
varying vec2 outTexture;
void main() {
gl_FragColor = texture(tex, outTexture);
}
Emulator runs on android 5.1.1.
