Texture Mapping in Android OpenGL ES

Continue previous tutorial,

First create a new class named it Texture and put this code inside:

protected int textureId;
protected int width, height;
int resourceId;
boolean mipmaps;
private FloatBuffer tempTextureBuffer = null;

Texture(int resourceId, boolean mipmaps) {
this.resourceId = resourceId;
this.textureId = -1;
this.mipmaps = mipmaps;
}

Texture(int resourceId) {
this(resourceId, false);
}

private static final int newTextureID() {
int[] temp = new int[1];
GLES10.glGenTextures(1, temp, 0);
return temp[0];
}

public final int getWidth() {
return width;
}

public final int getHeight() {
return height;
}

public final void load(Context context) {

BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inScaled = false;
Bitmap bmp = BitmapFactory.decodeResource(context.getResources(), resourceId, opts);
width = bmp.getWidth();
height = bmp.getHeight();
textureId = newTextureID();
GLES10.glBindTexture(GL10.GL_TEXTURE_2D, textureId); GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bmp, 0); GLES10.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);

if(mipmaps) {
GLES20.glGenerateMipmap(GLES20.GL_TEXTURE_2D);
GLES10.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR_MIPMAP_LINEAR);
} else GLES10.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR);

bmp.recycle();

if(tempTextureBuffer == null)
buildTextureMapping();

}

private void buildTextureMapping() {

final float texture[] = {
0, 0,
1, 0,
0, 1,
1, 1,
};

final ByteBuffer ibb = ByteBuffer.allocateDirect(texture.length * 4);
ibb.order(ByteOrder.nativeOrder());
tempTextureBuffer = ibb.asFloatBuffer();
tempTextureBuffer.put(texture);
tempTextureBuffer.position(0);

}

public final void destroy() {
GLES10.glDeleteTextures(1, new int[] {textureId}, 0);
textureId = -1;
}

public final boolean isLoaded() {
return textureId >= 0;
}

public final void prepare(GL10 gl, int wrap) {
gl.glEnable(GL10.GL_TEXTURE_2D);
gl.glBindTexture(GL10.GL_TEXTURE_2D, textureId);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, wrap);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, wrap);
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, tempTextureBuffer);
}

public final void draw(GL10 gl, float x, float y, float w, float h, float rot) {
gl.glPushMatrix();
gl.glTranslatef(x, y, 0);
gl.glRotatef(rot, 0, 0, 1);
gl.glScalef(w, h, 0);
gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
gl.glPopMatrix();
}

Go to Stage class

Create a variable for class Texture and named it tex and create a String variable and named it img and create 3 float variable and named it xPos, yPos and r

Next clear everything inside onDrawFrame and replace with this code:

gl.glClear(GLES10.GL_COLOR_BUFFER_BIT);
tex.prepare(gl, GL10.GL_CLAMP_TO_EDGE);
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
tex.draw(gl, xPos, yPos, tex.getWidth()*r, tex.getHeight()*r, 0);

The draw function is we created inside the Texture class we call it inside Stage class by tex.draw() function, it's used to adjust the positioning and scaling of the texture

Add this code inside onSurfaceChanged method:

xPos = w/2;
yPos = h/2;
r=1;

Next add this code inside onSurfaceCreated method:

gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
tex.load(getContext());

Next copy a image and paste it inside the drawable folder in the project structure

Finally add this code inside the constructor of Stage class

img = "YOUR_IMAGE_NAME";
tex = new Texture(getResources().getIdentifier(img, "drawable", context.getPackageName()));

Finally output:

Video Tutorial: Click here