我是新手OpenGL,正在尝试将纹理映射到一个正方形上。我遵循了NeHe的纹理映射教程:
http://insanitydesign.com/wp/wp-content/uploads/lesson06.zip。
现在我看到了我的图片...但它没有正确地映射。以下是原始图片:
http://ge.tt/2FzsdIx。
这是我所看到的:
http://ge.tt/6y3cdIu。
我使用了来自这个伟大的iPhone教程(下面链接)中的顶点和纹理数组,所以我希望它们已经被正确地映射。以下是Square.java代码的链接,谢谢!
public class Square {
// Our vertices.
private float vertices[] = {
-1.0f, 1.0f, 0.0f, // 0, Top Left
-1.0f, -1.0f, 0.0f, // 1, Bottom Left
1.0f, -1.0f, 0.0f, // 2, Bottom Right
1.0f, 1.0f, 0.0f, // 3, Top Right
};
// The order we like to connect them.
private short[] indices = { 0, 1, 2, 0, 2, 3 };
// Our vertex buffer.
private FloatBuffer vertexBuffer;
// Our index buffer.
private ShortBuffer indexBuffer;
/** The buffer holding the texture coordinates */
private FloatBuffer textureBuffer;
//the texture pointer, holds the texture name which is actually a number.
private int[] textures = new int[1];
public Square() {
// a float is 4 bytes, therefore we multiply the number if
// vertices with 4.
ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4);
vbb.order(ByteOrder.nativeOrder());
vertexBuffer = vbb.asFloatBuffer();
vertexBuffer.put(vertices);
vertexBuffer.position(0);
// short is 2 bytes, therefore we multiply the number if
// vertices with 2.
ByteBuffer ibb = ByteBuffer.allocateDirect(indices.length * 2);
ibb.order(ByteOrder.nativeOrder());
indexBuffer = ibb.asShortBuffer();
indexBuffer.put(indices);
indexBuffer.position(0);
//plot our texture
float textCoords[]={
//Mapping coordinates for the vertices
0.0f, 1.0f,
1.0f, 1.0f,
0.0f, 0.0f,
1.0f, 0.0f
};
ByteBuffer tbb = ByteBuffer.allocateDirect(textCoords.length * 4); tbb.order(ByteOrder.nativeOrder());
textureBuffer = tbb.asFloatBuffer(); textureBuffer.put(textCoords);
textureBuffer.position(0);
}
//load our texture(s)
static void loadTexture(GL10 gl, Context context, int resource) {
Bitmap bmp = BitmapFactory.decodeResource(context.getResources(),resource);
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bmp, 0);
gl.glTexParameterx(GL10.GL_TEXTURE_2D,
GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR);
gl.glTexParameterx(GL10.GL_TEXTURE_2D,
GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
bmp.recycle();
}
/**
* This function draws our square on screen.
* @param gl
*/
public void draw(GL10 gl) {
//use our textures
gl.glEnable(GL10.GL_TEXTURE_2D); // workaround bug 3623
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer);
// Counter-clockwise winding.
gl.glFrontFace(GL10.GL_CCW); // OpenGL docs
// Enable face culling.
gl.glEnable(GL10.GL_CULL_FACE); // OpenGL docs
// What faces to remove with the face culling.
gl.glCullFace(GL10.GL_BACK); // OpenGL docs
// Enabled the vertices buffer for writing and to be used during
// rendering.
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);// OpenGL docs.
// Specifies the location and data format of an array of vertex
// coordinates to use when rendering.
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, // OpenGL docs
vertexBuffer);
gl.glDrawElements(GL10.GL_TRIANGLES, indices.length,// OpenGL docs
GL10.GL_UNSIGNED_SHORT, indexBuffer);
// Disable the vertices buffer.
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); // OpenGL docs
// Disable face culling.
gl.glDisable(GL10.GL_CULL_FACE); // OpenGL docs
}
}
本文介绍了如何在OpenGL ES中使用纹理和纹理映射。涵盖了从创建位图到将其与几何形状结合的过程。此外,还讨论了使用纹理时需要考虑的一些性能问题。