对于很多初学者,视图投影之类非常的难理解,然而这个东西非常非常的重要,如果不是非常清楚,根本无法定位3D Object(空间坐标)和观察角度(观察角度不一样,效果就不一样),自己阅博无数,发现了一篇非常棒的blog文章:
http://blog.csdn.net/kesalin/article/details/7168967
由于尽量保证自己博客的原创性,所以不方便装载,所以reviewer一定要看上面链接的文章,图文并茂,然后通过自己的测试程序进行测试,就会彻底明白.当然这个博主是苹果APP的,但是没有关系,理论是通用的.
这里大致总结一下:
概念一:
a> : viewport(视口)变换 : 结合程序,下面是定义点的坐标,平时看sample比较多就会发现,x,y,z轴都用标量为1去设置
private float vertexs[]={ 0.0f,0.0f,0.0f, 1.0f,0.0f,0.0f, 0.0f,1.0f,0.0f };
但是显示在移动设备屏幕上是一个3D图像,但是这个1是如何转换到屏幕的呢?这个1即不代表像素,又没有代表一个比例(比如1:500,1代表占用500像素),却在程序运行后显示一个3D图形.这个地方就是上面博客中提到的:从 Normalized Device Space 到 Window Space 就是 viewport 变换过程:
看看上面的,程序中设置就是Normalized Device Space上的"坐标",如果要显示在移动设备的屏幕上,就需要一个转换,转换规则
其中上面转换公式中的参数,x,y,width,height是通过:
glViewport(x, y, width, height);
设置的;
(xw, yw)是屏幕坐标;
(xnd, ynd)是投影之后经归一化之后的点(上图中 Normalized Device Space 空间的点);
概念二 :
b> : 模型视图变换 : 这里分两种,
1> : 变换3D Object在空间中的位置和旋转,而观察者(很多地方表述为:Camera)的位置保持不变;
2> : 保持3D Object在空间中的位置和旋转不变,观察者的位置变化.
所以当需要观察3D Object的不同角度的时候,可以通过变换3D Object的位置或角度,也可以变换观察者的位置或角度.
如果变化3D Object可以通过矩阵平移,旋转,缩放等操作;
如果变化观察者角度 :
gluLookAt(eyex, eyey, eyez, centerx, centery, centerz, upx, upy, upz);
eye 表示 camera/viewer 的位置, center 表示相机或眼睛的焦点(它与 eye 共同来决定 eye 的朝向),而 up 表示 eye 的正上方向,注意 up 只表示方向,与大小无关。通过调用此函数,就能够设定观察的场景,在这个场景中的物体就会被 OpenGL 处理。在 OpenGL 中,eye 的默认位置是在原点,指向 Z 轴的负方向(屏幕往里),up 方向为 Y 轴的正方向.
概念三 :
c> : 投影变换 : 投影变换的目的是确定 3D 空间的物体如何投影到 2D 平面上,从而形成2D图像,这些 2D 图像再经视口变换就被渲染到屏幕上;
这个也包含两种情况:
1> : 正交投影;
2> : 透视投影;
1> : 正交投影:可以把正交投影看成是透视投影的特殊形式:即近裁剪面与远裁剪面除了Z 位置外完全相同,因此物体始终保持一致的大小,即便是在远处看上去也不会变小.
这个图其实非常好了,但是觉得还差一样东西,就可以更明白了,3D Object物体,这个物体一般如果想被观察者看到,就需要将3D物体放在上面的那个立体盒子中(当然很多情况通过设置了near,far会将3D物体"放在盒子外面了"),也就是说,要想看到3D物理,首先需要将其置于两个切面之间(即图中黑色斜线面和蓝绿色斜线面之间),同时如果有必要还需要将3D物理进行缩放操作(这样方便从黑色斜面观察进去).
设置正交投影:
glOrtho(left, right, bottom, top, zNear, zFar);
left,right, bootom,top 定义了 near 裁剪面大小,而 zNear 和 zFar 定义了从 Camera/Viewer 到远近两个裁剪面的距离(注意这两个距离都是正值).
2> : 透视投影:这个地方由于使用的库不一样,存在两种:
<I> : OpenGL es提供的模型:
glFrustum(left, right, bottom, top, zNear, zFar);
left,right, bootom,top 定义了 near 裁剪面大小,而 zNear 和 zFar 定义了从 Camera/Viewer 到远近两个裁剪面的距离(注意这两个距离都是正值)。由这六个参数可以定义出六个裁剪面构成的锥体,这个锥体通常被称之为视锥体或视景体。只有在这个锥体内的物体才是可以见的,不在这个锥体内的物体就相当于不再视线范围内,因而会被裁减掉,OpenGL
不会这些物体进行渲染
通过glFrustum机型设置该模型!
<II> : glut辅助库模型如下:
注意这个模型和上面模型的标注部分,样子是一样的,但是标注是不一样的.
gluPerspective(fovy, aspect, zNear, zFar);
fovy 定义了 camera 在 y 方向上的视线角度(介于 0 ~ 180 之间),aspect 定义了近裁剪面的宽高比 aspect = w/h,而 zNear 和 zFar 定义了从 Camera/Viewer 到远近两个裁剪面的距离(注意这两个距离都是正值)。这四个参数同样也定义了一个视锥体。
在 OpenGL ES 2.0 中,我们也需要自己实现该函数。我们可以通过三角公式 tan(fovy/2) = (h / 2)/zNear 计算出 h ,然后再根据 w = h * aspect 计算出 w,这样就可以得到 left, right, top, bottom, zNear, zFar 六个参数,代入在介绍视锥体时提到的公式即可.
补充两个图:
结论:
注意
写 OpenGL 代码时从前到后的顺序依次是:设定 viewport(视口变换),设定投影变换,设定视图变换,设定模型变换,在本地坐标空间描绘物体。而在前面为了便于理解做介绍时,说的顺序是OpenGL 中物体最初是在本地坐标空间中,然后转换到世界坐标空间,再到 camera 视图空间,再到投影空间。由于模型变换包括了本地空间变换到世界坐标空间,所以我们理解3D 变换是一个顺序,而真正写代码时则是以相反的顺序进行的,如果从左乘矩阵这点上去理解就很容易明白为什么会是反序的
根据这个可以做一个Android Demo测试一下Android studio工程[]:
代码片区如下:
package org.pumpkin.pumpkintutor2gsls; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import org.pumpkin.pumpkintutor2gsls.tutor2.cube.CubeSurfaceView; import org.pumpkin.pumpkintutor2gsls.tutor2.triangle.TriangleSurfaceView; import org.pumpkin.pumpkintutor2gsls.tutor2.triangle1.TriangleSurfaceView1; public class PumpKinMainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new TriangleSurfaceView1(this)/*new CubeSurfaceView(this)*//*new TriangleSurfaceView(this)*/); } }
package org.pumpkin.pumpkintutor2gsls.tutor2.triangle1; import android.content.Context; import android.opengl.GLSurfaceView; import org.pumpkin.pumpkintutor2gsls.tutor2.triangle.TriangleRenderer; /** * Project name : PumpKinTutor2Gsls * Created by zhibao.liu on 2016/5/18. * Time : 11:18 * Email [email protected] * Action : durian */ public class TriangleSurfaceView1 extends GLSurfaceView { public TriangleSurfaceView1(Context context) { super(context); this.setEGLContextClientVersion(2); //fix for error No Config chosen, but I don't know what this does. super.setEGLConfigChooser(8 , 8, 8, 8, 16, 0); this.setRenderer(new TriangleRenderer1(context)); // Render the view only when there is a change in the drawing data setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY); } }
package org.pumpkin.pumpkintutor2gsls.tutor2.triangle1; import android.content.Context; import android.opengl.GLES20; import android.opengl.GLSurfaceView; import android.opengl.Matrix; import android.os.SystemClock; import org.pumpkin.pumpkintutor2gsls.tutor2.coord.Coord; import javax.microedition.khronos.egl.EGLConfig; import javax.microedition.khronos.opengles.GL10; /** * Project name : PumpKinTutor2Gsls * Created by zhibao.liu on 2016/5/18. * Time : 11:17 * Email [email protected] * Action : durian */ public class TriangleRenderer1 implements GLSurfaceView.Renderer { private float[] mMVPMatrix = new float[16]; private float[] mViewMatrix = new float[16]; private float[] mModelMatrix = new float[16]; private float[] mProjectionMatrix = new float[16]; private Context mContext; private Triangle1 triangle1; private Coord coord; public TriangleRenderer1(Context context) { mContext = context; } @Override public void onSurfaceCreated(GL10 gl, EGLConfig config) { GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); GLES20.glEnable(GLES20.GL_CULL_FACE); GLES20.glEnable(GLES20.GL_DEPTH_TEST); triangle1 = new Triangle1(mContext); triangle1.loadTexture(); coord = new Coord(mContext); // Position the eye behind the origin. final float eyeX = 0.0f; final float eyeY = 0.0f; final float eyeZ = 0.0f; // We are looking toward the distance final float lookX = 0.0f; final float lookY = 0.0f; final float lookZ = -1.0f; // Set our up vector. This is where our head would be pointing were we holding the camera. final float upX = 0.0f; final float upY = 1.0f; final float upZ = 0.0f; // Set the view matrix. This matrix can be said to represent the camera position. // NOTE: In OpenGL 1, a ModelView matrix is used, which is a combination of a model and // view matrix. In OpenGL 2, we can keep track of these matrices separately if we choose. Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, lookX, lookY, lookZ, upX, upY, upZ); } @Override public void onSurfaceChanged(GL10 gl, int width, int height) { GLES20.glViewport(0, 0, width, height); final float ratio = (float) width / height; final float left = -ratio; final float right = ratio; final float bottom = -1.0f; final float top = 1.0f; final float near = 1.0f; final float far = 10.0f; Matrix.frustumM(mProjectionMatrix, 0, left, right, bottom, top, near, far); } @Override public void onDrawFrame(GL10 gl) { GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); Matrix.setIdentityM(mModelMatrix, 0); Matrix.translateM(mModelMatrix, 0, 0.0f, 0.0f, -5.0f); Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0); triangle1.draw(mMVPMatrix); coord.draw(mMVPMatrix); } }
在上面的渲染器中,调整setLookAtM参数,以及frustumM参数,在运行既可以发现视角在变化.
package org.pumpkin.pumpkintutor2gsls.tutor2.triangle1; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.opengl.GLES20; import android.opengl.GLUtils; import org.pumpkin.pumpkintutor2gsls.R; import org.pumpkin.pumpkintutor2gsls.shader.PumpKinShader; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; /** * Project name : PumpKinTutor2Gsls * Created by zhibao.liu on 2016/5/18. * Time : 11:17 * Email [email protected] * Action : durian */ public class Triangle1 { private FloatBuffer vertexsBuffer; private FloatBuffer colorsBuffer; private FloatBuffer texturesBuffer; private int mMVPMatrixHandle; private int mPositionHandle; private int mColorHandle; private int mTextureCoordsHandle; private int mProgram; private Context mContext; private Bitmap bitmap; private int[] textures=new int[1]; private float vertexs[]={ 0.0f,0.0f,0.0f, 2.0f,0.0f,0.0f, 0.0f,2.0f,0.0f }; private float colors[]={ 1.0f,0.0f,0.0f,1.0f, 0.0f,1.0f,0.0f,1.0f, 0.0f,0.0f,1.0f,1.0f }; private float textureCoords[]={ /*0,0, 1,0, 0,1*/ 0,1, 1,0, 0,0 }; public Triangle1(Context context){ mContext=context; ByteBuffer vbb=ByteBuffer.allocateDirect(vertexs.length*4); vbb.order(ByteOrder.nativeOrder()); vertexsBuffer=vbb.asFloatBuffer(); vertexsBuffer.put(vertexs); vertexsBuffer.position(0); ByteBuffer cbb=ByteBuffer.allocateDirect(colors.length*4); cbb.order(ByteOrder.nativeOrder()); colorsBuffer=cbb.asFloatBuffer(); colorsBuffer.put(colors); colorsBuffer.position(0); ByteBuffer tbb=ByteBuffer.allocateDirect(textureCoords.length*4); tbb.order(ByteOrder.nativeOrder()); texturesBuffer=tbb.asFloatBuffer(); texturesBuffer.put(textureCoords); texturesBuffer.position(0); String vshaderCode= PumpKinShader.loadGsls(mContext,0); String fshaderCode=PumpKinShader.loadGsls(mContext,1); int mvShaderHandle= GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER); if(mvShaderHandle!=0) { GLES20.glShaderSource(mvShaderHandle, vshaderCode); GLES20.glCompileShader(mvShaderHandle); int[] status=new int[1]; GLES20.glGetShaderiv(mvShaderHandle,GLES20.GL_COMPILE_STATUS,status,0); if(status[0]==0){ GLES20.glDeleteShader(mvShaderHandle); mvShaderHandle=0; } } if(mvShaderHandle==0){ throw new RuntimeException("failed to create vertex shader !"); } int mfShaderHandle=GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER); if(mfShaderHandle!=0){ GLES20.glShaderSource(mfShaderHandle,fshaderCode); GLES20.glCompileShader(mfShaderHandle); int[] status=new int[1]; GLES20.glGetShaderiv(mfShaderHandle,GLES20.GL_COMPILE_STATUS,status,0); if(status[0]==0){ GLES20.glDeleteShader(mfShaderHandle); mfShaderHandle=0; } } if(mfShaderHandle==0){ throw new RuntimeException("failed to create fragment shader !"); } mProgram=GLES20.glCreateProgram(); if(mProgram!=0){ GLES20.glAttachShader(mProgram,mvShaderHandle); GLES20.glAttachShader(mProgram,mfShaderHandle); GLES20.glLinkProgram(mProgram); int[] linkstatus=new int[1]; GLES20.glGetProgramiv(mProgram,GLES20.GL_LINK_STATUS,linkstatus,0); if(linkstatus[0]==0){ GLES20.glDeleteProgram(mProgram); mProgram=0; } } if(mProgram==0){ throw new RuntimeException("failed to create program !"); } } public void draw(float[] mvpmatrix){ GLES20.glUseProgram(mProgram); mPositionHandle=GLES20.glGetAttribLocation(mProgram,"a_Position"); GLES20.glVertexAttribPointer(mPositionHandle,3,GLES20.GL_FLOAT,false,0,vertexsBuffer); GLES20.glEnableVertexAttribArray(mPositionHandle); mColorHandle=GLES20.glGetAttribLocation(mProgram,"a_Color"); GLES20.glVertexAttribPointer(mColorHandle,4,GLES20.GL_FLOAT,false,0,colorsBuffer); GLES20.glEnableVertexAttribArray(mColorHandle); mTextureCoordsHandle=GLES20.glGetAttribLocation(mProgram,"a_inputTextureCoordinate"); GLES20.glVertexAttribPointer(mTextureCoordsHandle,2,GLES20.GL_FLOAT,false,0,texturesBuffer); GLES20.glEnableVertexAttribArray(mTextureCoordsHandle); mMVPMatrixHandle=GLES20.glGetUniformLocation(mProgram,"u_MVPMatrix"); PumpKinShader.checkGLError("glGetUniformLocation"); GLES20.glUniformMatrix4fv(mMVPMatrixHandle,1,false,mvpmatrix,0); PumpKinShader.checkGLError("glUniformMatrix4fv"); GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP,0,3); GLES20.glDisableVertexAttribArray(mPositionHandle); GLES20.glDisableVertexAttribArray(mColorHandle); GLES20.glDisableVertexAttribArray(mTextureCoordsHandle); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D,0); GLES20.glDisable(GLES20.GL_BLEND); } public void loadTexture(){ GLES20.glGenTextures(1,textures,0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D,textures[0]); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D,GLES20.GL_TEXTURE_MAG_FILTER,GLES20.GL_LINEAR); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D,GLES20.GL_TEXTURE_MIN_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); bitmap= BitmapFactory.decodeResource(mContext.getResources(), R.drawable.src); GLUtils.texImage2D(GLES20.GL_TEXTURE_2D,0,bitmap,0); } }
辅助类:
package org.pumpkin.pumpkintutor2gsls.shader; import android.content.Context; import android.opengl.GLES20; import android.util.Log; import java.io.IOException; import java.io.InputStream; /** * Project name : PumpKinBasicGLSL * Created by zhibao.liu on 2016/5/11. * Time : 14:26 * Email [email protected] * Action : durian */ public class PumpKinShader { private final static String TAG="PumpKinShader"; private static int GLESVersion=20; public static void setVersion(int version){ switch (version){ case 20: GLESVersion=20; break; case 30: GLESVersion=30; break; default: GLESVersion=20; break; } } public static String loadGsls(Context context, int type){ String shadercode=""; String shaderfilename=""; switch (type){ case 0: shaderfilename="vshader.glsl"; break; case 1: shaderfilename="fshader.glsl"; break; case 2: shaderfilename="tvshader.glsl"; break; case 3: shaderfilename="tfshader.glsl"; break; case 4: shaderfilename="coordvshader.glsl"; break; case 5: shaderfilename="coordfshader.glsl"; break; } try { InputStream is=context.getResources().getAssets().open(shaderfilename); int length=is.available(); byte[] buffer=new byte[length]; int read = is.read(buffer); shadercode=new String(buffer);//buffer.toString(); } catch (IOException e) { e.printStackTrace(); } Log.i(TAG,"shadercode : "+shadercode); return shadercode; } public static int loadShader(int type,String shadercode){ int shader= GLES20.glCreateShader(type); GLES20.glShaderSource(shader,shadercode); GLES20.glCompileShader(shader); return shader; } public static void checkGLError(String glOperation){ int error; while((error=GLES20.glGetError())!=GLES20.GL_NO_ERROR){ throw new RuntimeException(glOperation+" : glError "+error); } } }
同样增加一个坐标显示:
package org.pumpkin.pumpkintutor2gsls.tutor2.coord; import android.content.Context; import android.opengl.GLES20; import org.pumpkin.pumpkintutor2gsls.shader.PumpKinShader; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; /** * Project name : PumpKinTutor2Gsls * Created by zhibao.liu on 2016/5/18. * Time : 15:36 * Email [email protected] * Action : durian */ public class Coord { private FloatBuffer vertexsBuffer; private FloatBuffer colorsBuffer; private int mPositionHandle; private int mColorHandle; private int mMVPMatrixHandle; private int mProgram; private Context mContext; private float[] vertexs={ 0,0,0, 5,0,0, 0,0,0, 0,5,0, 0,0,0, 0,0,5 }; private float[] colors={ 1.0f,0.0f,0.0f,1.0f, 1.0f,0.0f,0.0f,1.0f, 0.0f,1.0f,0.0f,1.0f, 0.0f,1.0f,0.0f,1.0f, 0.0f,0.0f,1.0f,1.0f, 0.0f,0.0f,1.0f,1.0f }; public Coord(Context context){ mContext=context; ByteBuffer vbb=ByteBuffer.allocateDirect(vertexs.length*4); vbb.order(ByteOrder.nativeOrder()); vertexsBuffer=vbb.asFloatBuffer(); vertexsBuffer.put(vertexs); vertexsBuffer.position(0); ByteBuffer cbb=ByteBuffer.allocateDirect(colors.length*4); cbb.order(ByteOrder.nativeOrder()); colorsBuffer=cbb.asFloatBuffer(); colorsBuffer.put(colors); colorsBuffer.position(0); String vshaderCode= PumpKinShader.loadGsls(mContext,4); String fshaderCode=PumpKinShader.loadGsls(mContext,5); int vshaderHandle=GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER); if(vshaderHandle!=0){ GLES20.glShaderSource(vshaderHandle,vshaderCode); GLES20.glCompileShader(vshaderHandle); int[] status=new int[1]; GLES20.glGetShaderiv(vshaderHandle,GLES20.GL_COMPILE_STATUS,status,0); if(status[0]==0){ GLES20.glDeleteShader(vshaderHandle); vshaderHandle=0; } } int fshaderHandle=GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER); if(fshaderHandle!=0){ GLES20.glShaderSource(fshaderHandle,fshaderCode); GLES20.glCompileShader(fshaderHandle); int[] status=new int[1]; GLES20.glGetShaderiv(fshaderHandle,GLES20.GL_COMPILE_STATUS,status,0); if(status[0]==0){ GLES20.glDeleteShader(fshaderHandle); fshaderHandle=0; } } if(fshaderHandle==0){ throw new RuntimeException("failed to create frag shader !"); } mProgram=GLES20.glCreateProgram(); if(mProgram!=0){ GLES20.glAttachShader(mProgram,vshaderHandle); GLES20.glAttachShader(mProgram,fshaderHandle); GLES20.glLinkProgram(mProgram); int[] linkstatus=new int[1]; GLES20.glGetProgramiv(mProgram,GLES20.GL_LINK_STATUS,linkstatus,0); if(linkstatus[0]==0){ GLES20.glDeleteProgram(mProgram); mProgram=0; } } if(mProgram==0){ throw new RuntimeException("failed to create program !"); } } public void draw(float[] mvpMatrix){ GLES20.glUseProgram(mProgram); mPositionHandle=GLES20.glGetAttribLocation(mProgram,"a_Position"); GLES20.glVertexAttribPointer(mPositionHandle,3,GLES20.GL_FLOAT,false,0,vertexsBuffer); GLES20.glEnableVertexAttribArray(mPositionHandle); mColorHandle=GLES20.glGetAttribLocation(mProgram,"a_Color"); GLES20.glVertexAttribPointer(mColorHandle,4,GLES20.GL_FLOAT,false,0,colorsBuffer); GLES20.glEnableVertexAttribArray(mColorHandle); mMVPMatrixHandle=GLES20.glGetUniformLocation(mProgram,"u_MvpMatrix"); PumpKinShader.checkGLError("glGetUniformLocation"); GLES20.glUniformMatrix4fv(mMVPMatrixHandle,1,false,mvpMatrix,0); PumpKinShader.checkGLError("glUniformMatrix4fv"); GLES20.glDrawArrays(GLES20.GL_LINES,0,vertexs.length/3); GLES20.glDisableVertexAttribArray(mColorHandle); GLES20.glDisableVertexAttribArray(mPositionHandle); } }
下面是glsl脚本:
vshader.glsl :
uniform mat4 u_MVPMatrix; uniform vec4 u_Color; attribute vec4 a_Position; attribute vec4 a_Color; attribute vec4 a_inputTextureCoordinate; varying vec2 textureCoordinate; varying vec4 v_Color; void main(){ gl_Position=u_MVPMatrix*a_Position; v_Color=a_Color; textureCoordinate=a_inputTextureCoordinate.xy; }
gshader.glsl :
precision mediump float; varying vec4 v_Color; varying highp vec2 textureCoordinate; uniform sampler2D inputImageTexture; void main(){ gl_FragColor=v_Color*texture2D(inputImageTexture,textureCoordinate); }
坐标对应的glsl脚本:
coordvshader.glsl:
uniform mat4 u_MvpMatrix; attribute vec4 a_Position; attribute vec4 a_Color; varying vec4 v_Color; void main() { gl_Position=u_MvpMatrix*a_Position; v_Color=a_Color; }
coordfshader.glsl :
precision mediump float; varying vec4 v_Color; void main() { gl_FragColor=v_Color; }
另外在drawable下面增加一个src.png的图片/
运行结果:
最后:下载Nate Robin tutors-win32.zip这个包,里面有3D模拟器,可以通过3D模拟器参数设置观察效果,从而进一步理解上面的理论.这个模拟器可以说是神器啊!