編輯:關於Android編程
要是做復雜的OpenGL應用程序,一定會用到紋理技術。紋理說白了就是把圖片或者視頻圖像繪制到OpenGL空間中。
因此紋理也有坐標系,稱ST坐標,或者UV
上面是紋理坐標空間,但沒有固定的方向
下面演示加載一張image作為紋理貼圖。
public class TextureUtils { public static int createTexture(InputStream ins) { int[] textures = new int[1]; GLES20.glGenTextures(1, textures, 0);//生成一個紋理 int textureId = textures[0]; GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER,GLES20.GL_NEAREST); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D,GLES20.GL_TEXTURE_MAG_FILTER,GLES20.GL_LINEAR); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S,GLES20.GL_CLAMP_TO_EDGE); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T,GLES20.GL_CLAMP_TO_EDGE); //上面是紋理貼圖的取樣方式,包括拉伸方式,取臨近值和線性值 Bitmap bitmap = BitmapFactory.decodeStream(ins); GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);//讓圖片和紋理關聯起來,加載到OpenGl空間中 Log.d(OPENGL,bitmap: + bitmap); bitmap.recycle();//不需要,可以釋放 return textureId; } }
public class MyRenderer implements Renderer { public static float[] projMatrix = new float[16];// 投影 public static float[] viewMatrix = new float[16];// 相機 public static float[] mViewPjMatrix;// 總變換矩陣 public static float[] matrixs = new float[16]; public static int textureId = -1; Context context; MyDrawModel drawModel; public MyRenderer(Context context) { this.context = context; } @Override public void onDrawFrame(GL10 arg0) { GLES20.glClear( GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT); Log.e(, textureId: + textureId); drawModel.drawFrame(textureId); } @Override public void onSurfaceChanged(GL10 arg0, int w, int h) { GLES20.glViewport(0, 0, w, h); float ratio = (float) w / h; Matrix.frustumM(projMatrix, 0, -ratio, ratio, -1, 1, 1, 10);//投影矩陣設置 Matrix.setLookAtM(viewMatrix, 0, 0, 0, 3, 0, 0, 0, 0.0f, 1.0f, 0.0f);//攝像機坐標設置 } @Override public void onSurfaceCreated(GL10 g, EGLConfig eglConfig) { GLES20.glClearColor(0.5f,0.5f,0.5f, 1.0f); GLES20.glEnable(GLES20.GL_DEPTH_TEST); InputStream ins = null; drawModel = new MyDrawModel(); drawModel.init(); try { ins = context.getAssets().open(house.jpg); textureId = TextureUtils.createTexture(ins); Log.e(, textureId: + textureId); } catch (IOException e) { e.printStackTrace(); } finally { try { ins.close(); } catch (IOException e) { e.printStackTrace(); } } GLES20.glDisable(GLES20.GL_CULL_FACE); } }
public class MyDrawModel { private int programId; private int mVPMatrixHandle; // 總變換矩陣引用id private int positionHandle; // 頂點位置id private int texCoorHandle; // 頂點紋理坐標id private FloatBuffer vertexBuffer; private FloatBuffer texCoorBuffer; public MyDrawModel() { } public void init() { initData(); int vertexsharder = GLHelper.compileScript(GLES20.GL_VERTEX_SHADER, GLScript.vertex2); int fragmentsharder = GLHelper.compileScript(GLES20.GL_FRAGMENT_SHADER, GLScript.fragment2); programId = GLHelper.linkAttach(vertexsharder, fragmentsharder); boolean isOK = GLHelper.checkProgram(programId); positionHandle = GLES20.glGetAttribLocation(programId, aPosition); texCoorHandle = GLES20.glGetAttribLocation(programId, aTexCoor); mVPMatrixHandle = GLES20.glGetUniformLocation(programId, uMVPMatrix); Log.d(OPENGL, positionHandle: + positionHandle + ;texCoorHandle: + texCoorHandle + ;mVPMatrixHandle: + mVPMatrixHandle + ; + isOK); } private void initData() { //X,Y,Z,繪畫的頂點 float vertices[] = new float[] { 0, 0, 0, -1.8f, -1f, 0, 1.8f, -1f, 0, 1.8f, 1f, 0, -1.8f, 1f, 0, -1.8f, -1f, 0 }; ByteBuffer vb = ByteBuffer.allocateDirect(vertices.length * 4); vb.order(ByteOrder.nativeOrder()); vertexBuffer = vb.asFloatBuffer(); vertexBuffer.put(vertices); vertexBuffer.position(0); //紋理空間坐標 S,T float texCoor[] = new float[] { 0.5f, 0.5f, 0f, 1f, 1f, 1f, 1f, 0f, 0f, 0f, 0f, 1f }; ByteBuffer cb = ByteBuffer.allocateDirect(texCoor.length * 4); cb.order(ByteOrder.nativeOrder()); texCoorBuffer = cb.asFloatBuffer(); texCoorBuffer.put(texCoor); texCoorBuffer.position(0); } public void drawFrame(int textureId) { GLES20.glUseProgram(programId); // // 初始化矩陣 Matrix.setRotateM(MyRenderer.matrixs, 0, 0, 1, 0, 0); Matrix.translateM(MyRenderer.matrixs, 0, 0, 0, 1); //矩陣轉換 ,投影矩陣,攝像機矩陣,模型矩陣 MyRenderer.mViewPjMatrix = new float[16]; Matrix.multiplyMM(MyRenderer.mViewPjMatrix, 0, MyRenderer.viewMatrix,0, MyRenderer.matrixs, 0); Matrix.multiplyMM(MyRenderer.mViewPjMatrix, 0, MyRenderer.projMatrix,0, MyRenderer.mViewPjMatrix, 0); GLES20.glUniformMatrix4fv(mVPMatrixHandle, 1, false, MyRenderer.mViewPjMatrix, 0); GLES20.glVertexAttribPointer(positionHandle, 3, GLES20.GL_FLOAT, false, 3 * 4, vertexBuffer); GLES20.glVertexAttribPointer(texCoorHandle, 2, GLES20.GL_FLOAT, false, 2 * 4, texCoorBuffer); GLES20.glEnableVertexAttribArray(positionHandle); GLES20.glEnableVertexAttribArray(texCoorHandle); GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId); GLES20.glDrawArrays(GLES20.GL_TRIANGLE_FAN, 0, 6);//六個定點,繪制三角形 } }
public class GLScript { public GLScript() { } public static final String vertex1 = attribute vec4 mPosition; + void main() + { + gl_Position=mPosition; + } ; public static final String fragment1 = precision mediump float; + uniform vec4 mColor; + void main(){ gl_FragColor=mColor; }; public static final String vertex2 = uniform mat4 uMVPMatrix; + attribute vec3 aPosition; + attribute vec2 aTexCoor; + varying vec2 vTextureCoord; + void main() { + gl_Position = uMVPMatrix * vec4(aPosition,1); + vTextureCoord = aTexCoor; + } ; public static final String fragment2 = precision mediump float; + varying vec2 vTextureCoord; + uniform sampler2D sTexture; + void main() { + vec2 coord = vTextureCoord; + coord.s = coord.s * 0.5; //其實是去圖像的一半,向量縮小了 + gl_FragColor = texture2D(sTexture, coord); + } ; }
coord.s = coord.s * 0.5;這樣是取紋理圖像的一半,顯示到界面上也就是圖片的前半部分內容
其它的工具類和上一篇文章一樣。
內容顯示
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