i'm trying to develop a simple opengl ES 1.1 app that must show a
square polygon with a texture. The texture haves a rectangular
resolution of 1536x2048 pixels.
I'm learning opengl with the NEHE tutorials, but they didn't eplain
how to create a polygon with the dimensions of the textures.
This is my actual square.java code, it is doing it by the wrong way.
It receives a bitmap as parameter, and it creates a new scaled bitmap
with square form with POT dimensions, but with square proportions,
this code uses a square polygon, and i dont need that.
what i need to modify to create this polygon with the dimensions of
the texture?
public class Square {
//Buffer de vertices
private FloatBuffer vertexBuffer;
//Buffer de coordenadas de texturas
private FloatBuffer textureBuffer;
//Puntero de texturas
private int[] textures = new int[3];
//El item a representar
private Bitmap image;
//Definición de vertices
private float vertices[] =
{
-1.0f, -1.0f, 0.0f, //Bottom Left
1.0f, -1.0f, 0.0f, //Bottom Right
-1.0f, 1.0f, 0.0f, //Top Left
1.0f, 1.0f, 0.0f //Top Right
};
private float texture[] =
{
//Mapping coordinates for the vertices
0.0f, 1.0f,
1.0f, 1.0f,
0.0f, 0.0f,
1.0f, 0.0f
};
// Image ratio
float ratio;
//Inicializamos los buffers
public Square(Bitmap image) {
ByteBuffer byteBuf = ByteBuffer.allocateDirect(vertices.length
* 4);
byteBuf.order(ByteOrder.nativeOrder());
vertexBuffer = byteBuf.asFloatBuffer();
vertexBuffer.put(vertices);
vertexBuffer.position(0);
byteBuf = ByteBuffer.allocateDirect(texture.length * 4);
byteBuf.order(ByteOrder.nativeOrder());
textureBuffer = byteBuf.asFloatBuffer();
textureBuffer.put(texture);
textureBuffer.position(0);
this.image=image;
ratio = (float)image.getWidth() / image.getHeight();
}
//Funcion de dibujado
public void draw(GL10 gl) {
gl.glFrontFace(GL10.GL_CCW);
//gl.glEnable(GL10.GL_BLEND);
//Bind our only previously generated texture in this case
gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
//Point to our vertex buffer
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer);
//Enable vertex buffer
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
//Draw the vertices as triangle strip
gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, vertices.length /
3);
//Disable the client state before leaving
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
//gl.glDisable(GL10.GL_BLEND);
}
//Carga de texturas
public void loadGLTexture(GL10 gl, Context context) {
//Generamos un puntero de texturas
gl.glGenTextures(1, textures, 0);
//y se lo asignamos a nuestro array
gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
//Creamos filtros de texturas
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);
//Diferentes parametros de textura posibles
GL10.GL_CLAMP_TO_EDGE
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
GL10.GL_REPEAT);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
GL10.GL_REPEAT);
//Get the texture from the Android resource directory
InputStream is=null;
Bitmap bitmap =image;
//con el siguiente código redimensionamos las imágenes que
sean mas grandes de 256x256.
int newW=bitmap.getWidth();
int newH=bitmap.getHeight();
float fact;
if (newH>256 || newW>256)
{
if (newH>256)
{
fact=(float)255/(float)newH; //porcentaje por el que
multiplicar para ser tamaño 256
newH=(int)(newH*fact); //altura reducida al porcentaje
necesario
newW=(int)(newW*fact); //anchura reducida al
porcentaje necesario
}
if (newW>256)
{
fact=(float)255/(float)newW; //porcentaje por el que
multiplicar para ser tamaño 256
newH=(int)(newH*fact); //altura reducida al porcentaje
necesario
newW=(int)(newW*fact); //anchura reducida al
porcentaje necesario
}
bitmap=Bitmap.createScaledBitmap(bitmap, newW, newH,
true);
}
//con el siguiente código transformamos imágenes no potencia
de 2 en imágenes potencia de 2 (pot)
//meto el bitmap NOPOT en un bitmap POT para que no aparezcan
texturas blancas.
int nextPot=256;
int h = bitmap.getHeight();
int w = bitmap.getWidth();
int offx=(nextPot-w)/2; //distancia respecto a la izquierda,
para que la imagen quede centrada en la nueva imagen POT
int offy=(nextPot-h)/2; //distancia respecto a arriba, para
que la imagen quede centrada en la nueva imagen POT
Bitmap bitmap2 = Bitmap.createBitmap(nextPot, nextPot,
Bitmap.Config.ARGB_8888); //crea un bitmap transparente gracias al
ARGB_8888
Canvas comboImage = new Canvas(bitmap2);
comboImage.drawBitmap(bitmap, offx, offy, null);
comboImage.save();
//Usamos Android GLUtils para espcificar una textura de 2
dimensiones para nuestro bitmap
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap2, 0);
//Checkeamos si el GL context es versión 1.1 y generamos los
Mipmaps por Flag. Si no, llamamos a nuestra propia implementación
if(gl instanceof GL11) {
gl.glTexParameterf(GL11.GL_TEXTURE_2D,
GL11.GL_GENERATE_MIPMAP, GL11.GL_TRUE);
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap2, 0);
} else {
buildMipmap(gl, bitmap2);
}
//Limpiamos los bitmaps
bitmap.recycle();
bitmap2.recycle();
}
//Nuestra implementación de MipMap. Escalamos el bitmap original
hacia abajo por factor de 2 y lo asignamos como nuevo nivel de mipmap
private void buildMipmap(GL10 gl, Bitmap bitmap) {
int level = 0;
int height = bitmap.getHeight();
int width = bitmap.getWidth();
while(height >= 1 || width >= 1) {
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, level, bitmap, 0);
if(height == 1 || width == 1) {
break;
}
level++;
height /= 2;
width /= 2;
Bitmap bitmap2 = Bitmap.createScaledBitmap(bitmap, width,
height, true);
bitmap.recycle();
bitmap = bitmap2;
}
}
}
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