[英]OpenGL ES, add texture to circle
我在OpenGL ES中繪制一個圓,添加紋理時,它被“添加”了4次而不是1次(請參見下圖)。
換句話說,就是我的照片x4。 我想要的是以圓圈中的一張圖片為中心的核武器符號。
下面是我的方法(在Circle類中),用於使用紋理繪制圓
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,texBuffer與vertexBuffer相同(也許是問題所在?),因為它必須具有相同數量的點,而且我不知道哪些點不是頂點。
以下是我加載紋理的方法以及為紋理設置頂點的方法。
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:添加了Circle類的構造函數
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);
}
您的問題是您的uv從-1變為1。 確保它們從0變為1。
竇的最低值為-1,最高為1。
公式將是
x = (c * x - s * y +1) *0.5f;
y = ( s * t + c * y +1)*0.5f;
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