OpenGL ES，將紋理添加到圓圈

Question

我在OpenGL ES中繪製了一個圓圈，添加紋理時，它被「添加」4次而不是1次（請參閱下圖）。

換句話說，這是我的照片X4。我想要的是核心符號集中在圓圈中的一張圖片中。

下面是我使用貼圖

public void drawTexture(GL10 gl) { 
    gl.glFrontFace(GL10.GL_CCW); // Front face in counter-clockwise orientation 
    gl.glEnable(GL10.GL_CULL_FACE); // Enable cull face 
    gl.glCullFace(GL10.GL_BACK); // Cull the back face (don't display) 

    // Enable vertex-array and define its buffer 
    gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); 
    gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); // Enable texture-coords-array 
    gl.glVertexPointer(2, GL10.GL_FLOAT, 0, vertexBuffer); 
    gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, texBuffer); // Define texture-coords 


    // Draw the primitives from the vertex-array directly 

    gl.glPushMatrix(); 
    gl.glTranslatef(0.0f, 0.0f, 1.0f); 
    gl.glDrawArrays(GL10.GL_TRIANGLE_FAN, 0, numberOfVertices); 
    gl.glPopMatrix(); 

    gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY); 
    gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); 
    gl.glDisable(GL10.GL_CULL_FACE); 

} 

目前畫圓法（在Circle類），該texBuffer是一樣的vertexBuffer（也許問題？），因爲它具有有相同數量的點，我不知道哪些點，如果不是頂點。

下面是我加載紋理的方法以及設置紋理頂點的方法。

public void loadTexture(GL10 gl, Context context) { 
    gl.glGenTextures(1, textureIDs, 0); // Generate texture-ID array 
    gl.glBindTexture(GL10.GL_TEXTURE_2D, textureIDs[0]); // Bind to texture ID 
    // Set up texture filters 
    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); 

    // Construct an input stream to texture image 
    InputStream istream = context.getResources().openRawResource(R.drawable.nuke); 
    Bitmap bitmap; 
    try { 
     // Read and decode input as bitmap 
     bitmap = BitmapFactory.decodeStream(istream); 
    } finally { 
     try { 
      istream.close(); 
     } catch (IOException e) { 
     } 
    } 

    // Build Texture from loaded bitmap for the currently-bind texture ID 
    GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0); 
    bitmap.recycle(); 
} 

private void setUpTextureVertices(float radius) { 
    float theta = (float) (2 * Math.PI/(numberOfVertices-1)); 
    float c = (float) Math.cos(theta); 
    float s = (float) Math.sin(theta); 
    float x = radius; 
    float y = 0; 

    for (int i = 0; i < numberOfVertices; i++) { 
     texVertices[i][0] = x; 
     texVertices[i][1] = y; 
     float t = x; 
     x = (c * x - s * y + 1) * 0.5f; 
     y = (s * t + c * y + 1) * 0.5f; 
    } 
} 

private void setUpVertices(float radius) { 
    float theta = (float) (2 * Math.PI/(numberOfVertices-1)); 
    float c = (float) Math.cos(theta); 
    float s = (float) Math.sin(theta); 
    float x = radius; 
    float y = 0; 

    for (int i = 0; i < numberOfVertices; i++) { 
     vertices[i][0] = x; 
     vertices[i][1] = y; 
     float t = x; 
     x = c * x - s * y; 
     y = s * t + c * y; 
    } 
} 

編輯：添加的構造函數Circle類

public Circle() { 

    setUpVertices(1.0f); 
    // Setup vertex-array buffer. Vertices in float. A float has 4 bytes 
    ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4 * 2); 
    vbb.order(ByteOrder.nativeOrder()); // Use native byte order 
    vertexBuffer = vbb.asFloatBuffer(); // Convert byte buffer to float 

    // Loop through the vertices and put them in the vertexbuffer 
    for (int i = 0; i < numberOfVertices; i++) { 
     for (int j = 0; j <= 1; j++) { 
      vertexBuffer.put(vertices[i][j]); // Copy data into buffer 
     } 
    } 
    vertexBuffer.position(0); // Rewind 

    setUpTextureVertices(1.0f); 

    // Setup texture-coords-array buffer, in float. An float has 4 bytes 
    ByteBuffer tbb = ByteBuffer.allocateDirect(vertices.length * 4 * 2); 
    tbb.order(ByteOrder.nativeOrder()); 
    texBuffer = tbb.asFloatBuffer(); 
    // Loop through the vertices and put them in the vertexbuffer 
    for (int i = 0; i < numberOfVertices; i++) { 
     for (int j = 0; j <= 1; j++) { 
      texBuffer.put(texVertices[i][j]); // Copy data into buffer 
     } 
    } 
    texBuffer.position(0); 
} 

Answer 1

你的問題是，你的紫外線從-1到1。確保他們從0到1。

的竇的最低值是-1，而最高變爲1

公式將是

x = (c * x - s * y +1) *0.5f; 
y = (s * t + c * y +1)*0.5f;