我是android opengl开发的新手。我想用android中的opengl-es 2.0填充多边形图像,如下图所示。我能够绘制正方形,三角形但不能用重复图像填充它。任何人都知道请帮助我。
Square.java
public class Square {
private final String vertexShaderCode =
"uniform mat4 uMVPMatrix;" +
"attribute vec4 vPosition;" +
"attribute vec2 a_TextureCoordinates;" +
"varying vec2 v_TextureCoordinates;" +
"void main() {" +
" gl_Position = uMVPMatrix * vPosition;" +
" v_TextureCoordinates = a_TextureCoordinates;" +
"}";
private final String fragmentShaderCode =
"precision mediump float;" +
"uniform sampler2D u_TextureUnit;"+
"varying vec2 v_TextureCoordinates;" +
"void main() {" +
" gl_FragColor = texture2D(u_TextureUnit, v_TextureCoordinates);" +
"}";
private final FloatBuffer vertexBuffer;
private final FloatBuffer textureBuffer;
private final ShortBuffer drawListBuffer;
private final int mProgram;
private int mPositionHandle;
private int mColorHandle;
private int mMVPMatrixHandle;
static final int COORDS_PER_VERTEX = 3;
static float squareCoords[] = {
-1.0f, 1.0f, 0.0f, // top left
1.0f, 1.0f, 0.0f, // top right
1.0f, -1.0f, 0.0f, // bottom right
-1.0f, -1.0f, 0.0f // bottom left
};
final float[] previewTextureCoordinateData =
{
0.0f,0.0f, // top left
1.0f,0.0f, // Top-right
1.0f,1.0f, // Bottom-right
0.0f,1.0f, // Bottom-left
};
private int textureDataHandle;
private int textureUniformHandle;
private int textureCoordinateHandle;
private final short drawOrder[] = { 0, 1, 2, 0, 2, 3 };
float color[] = { 0.2f, 0.709803922f, 0.898039216f, 1.0f };
private int loadTexture(final Context context, final int resourceId){ final int[] textureHandle = new int[1];
GLES20.glGenTextures(1, textureHandle, 0);
if (textureHandle[0] != 0)
{
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inScaled = false; // No pre-scaling
// Read in the resource
final Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), resourceId, options);
// Bind to the texture in OpenGL
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureHandle[0]);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GLES20.GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GLES20.GL_REPEAT);
// Set filtering
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
// Load the bitmap into the bound texture.
GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
// Recycle the bitmap, since its data has been loaded into OpenGL.
bitmap.recycle();
}
if (textureHandle[0] == 0)
{
throw new RuntimeException("Error loading texture.");
}
return textureHandle[0];}
public Square(Context c) {
// initialize vertex byte buffer for shape coordinates
ByteBuffer bb = ByteBuffer.allocateDirect(
// (# of coordinate values * 4 bytes per float)
squareCoords.length * 4);
bb.order(ByteOrder.nativeOrder());
vertexBuffer = bb.asFloatBuffer();
vertexBuffer.put(squareCoords);
vertexBuffer.position(0);
// initialize byte buffer for the draw list
ByteBuffer dlb = ByteBuffer.allocateDirect(
// (# of coordinate values * 2 bytes per short)
drawOrder.length * 2);
dlb.order(ByteOrder.nativeOrder());
drawListBuffer = dlb.asShortBuffer();
drawListBuffer.put(drawOrder);
drawListBuffer.position(0);
ByteBuffer texCoordinates = ByteBuffer.allocateDirect(previewTextureCoordinateData.length * 4);
texCoordinates.order(ByteOrder.nativeOrder());
textureBuffer = texCoordinates.asFloatBuffer();
textureBuffer.put(previewTextureCoordinateData);
textureBuffer.position(0);
// prepare shaders and OpenGL program
int vertexShader = MyGLRenderer.loadShader(
GLES20.GL_VERTEX_SHADER,
vertexShaderCode);
int fragmentShader = MyGLRenderer.loadShader(
GLES20.GL_FRAGMENT_SHADER,
fragmentShaderCode);
textureDataHandle = loadTexture(c, R.drawable.air_hockey_surface);
mProgram = GLES20.glCreateProgram(); // create empty OpenGL Program
GLES20.glAttachShader(mProgram, vertexShader); // add the vertex shader to program
GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
GLES20.glLinkProgram(mProgram); // create OpenGL program executables
}
public void draw(float[] mvpMatrix) {
// Add program to OpenGL environment
GLES20.glUseProgram(mProgram);
// get handle to vertex shader's vPosition member
mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
// Enable a handle to the triangle vertices
GLES20.glEnableVertexAttribArray(mPositionHandle);
// Prepare the triangle coordinate data
GLES20.glVertexAttribPointer(
mPositionHandle, COORDS_PER_VERTEX,
GLES20.GL_FLOAT, false,
vertexStride, vertexBuffer);
textureCoordinateHandle = GLES20.glGetAttribLocation(mProgram, "a_TextureCoordinates");
GLES20.glVertexAttribPointer(textureCoordinateHandle, 2, GLES20.GL_FLOAT, false,
0, textureBuffer);
GLES20.glEnableVertexAttribArray(textureCoordinateHandle);
textureUniformHandle = GLES20.glGetUniformLocation(mProgram, "u_TextureUnit");
MyGLRenderer.checkGlError("glGetUniformLocation");
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureDataHandle);
GLES20.glUniform1i(textureUniformHandle, 0);
// get handle to shape's transformation matrix
mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
MyGLRenderer.checkGlError("glGetUniformLocation");
// Apply the projection and view transformation
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mvpMatrix, 0);
MyGLRenderer.checkGlError("glUniformMatrix4fv");
// Draw the square
GLES20.glDrawElements(
GLES20.GL_TRIANGLES, drawOrder.length,
GLES20.GL_UNSIGNED_SHORT, drawListBuffer);
// Disable vertex array
GLES20.glDisableVertexAttribArray(mPositionHandle);
}}
答案 0 :(得分:3)
如果要重复纹理,则需要设置此类纹理坐标。纹理坐标是纹理中的相对像素位置,其中(0.0, 0,0)
是图像的左上角位置,(1.0, 1.0)
是右下角。现在无论顶点坐标如何,所显示的纹理部分始终都是相同的。在你的情况下,然后
final float[] previewTextureCoordinateData =
{
0.0f,0.0f, // top left
1.0f,0.0f, // Top-right
1.0f,1.0f, // Bottom-right
0.0f,1.0f, // Bottom-left
};
表示您将在对象上绘制整个纹理。要使其在每个维度中重复3次,您需要将它们相乘:
final float[] previewTextureCoordinateData =
{
0.0f,0.0f, // top left
1.0f*3.0,0.0f, // Top-right
1.0f*3.0,1.0f*3.0, // Bottom-right
0.0f,1.0f*3.0, // Bottom-left
};
纹理上已经启用了重复,因此应该是它。