OpenGL, how to set a monochrome texture to a colored shape?
- by Santiago
I'm developing on Android with OpenGL ES, I draw some cubes and I change its colors with glColor4f. Now, what I want is to give a more realistic effect on the cubes, so I create a monochromatic 8bit depth, 64x64 pixel size PNG file. I loaded on a texture, and here is my problem, witch is the way to combine the color and the texture to get a colorized and textured cubes onto the screen?
I'm not an expert on OpenGL, I tried this:
On create:
public void asignBitmap(GL10 gl, Bitmap bitmap)
{
int[] textures = new int[1];
gl.glGenTextures(1, textures, 0);
mTexture = textures[0];
gl.glBindTexture(GL10.GL_TEXTURE_2D, mTexture);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);
gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE, GL10.GL_REPLACE);
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_ALPHA, bitmap, 0);
ByteBuffer tbb = ByteBuffer.allocateDirect(texCoords.length * 4);
tbb.order(ByteOrder.nativeOrder());
mTexBuffer = tbb.asFloatBuffer();
for (int i = 0; i < 48; i++) mTexBuffer.put(texCoords[i]);
mTexBuffer.position(0);
}
And OnDraw:
public void draw(GL10 gl, int alphawires) {
gl.glColor4f(1.0f, 0.0f, 0.0f, 0.5f); //RED
gl.glBindTexture(GL10.GL_TEXTURE_2D, mTexture);
gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
gl.glEnable(GL10.GL_TEXTURE_2D);
gl.glEnable(GL10.GL_BLEND);
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, mTexBuffer);
//Set the face rotation
gl.glFrontFace(GL10.GL_CW);
//Point to our buffers
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
//Enable the vertex and color state
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
//Draw the vertices as triangles, based on the Index Buffer information
gl.glDrawElements(GL10.GL_TRIANGLES, 36, GL10.GL_UNSIGNED_BYTE, indexBuffer);
//Disable the client state before leaving
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glDisable(GL10.GL_BLEND);
gl.glDisable(GL10.GL_TEXTURE_2D);
}
I'm even not sure if I have to use a blend option, because I don't need transparency, but is a plus :)
