android ndk调用OpenGL 实现纹理贴图Texture

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https://blog.csdn.net/chrisfxs/article/details/34359265

首先必须说。国内在OpenGL这方面特别是ndk上的分享太太太少

这中间遇到非常多问题，而这些问题须要在书上。在网上，在各种资料上找。并且书上是java层调用。网上的缺少各种文件案例。仅仅有在java层研究，在各种案例中找须要的知识点，遇到问题终于仅仅有google搜外国站点才干解决。

顺便说下，尽管如今google被墙，除了翻墙还有个非常easy的办法上google。

http://www.gfsoso.com/

谷粉搜搜

接下来正文

——————————————————————————————

学习ndk应该都是从google配有的案例開始的吧：GL2JNIActivity

这个案例就是一个会变颜色的背景加一个绿色三角形

由于我開始学习纹理贴图，所以打算将三角形换成贴图

首先须要配置纹理

在GL2JNIView.java中改动Renderer类

 private static class Renderer implements GLSurfaceView.Renderer {
        public void onDrawFrame(GL10 gl) {
            GL2JNILib.step();
        }

        public void onSurfaceChanged(GL10 gl, int width, int height) {
            GL2JNILib.init(width, height);
        }
        
        
        private Context mContext;
        int textureId;
        private int[] TextureString = new int[1];
        public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        	mContext = GL2JNIActivity.getContext();
        	
            //Bitmap bitmap = getBitmap(mContext,R.drawable.bac);
            Bitmap bitmap = getBitmap(mContext,R.drawable.wall);
            if(bitmap != null)
            {
            	Log.e("step", "bing the texture succeed!");
            	gl.glEnable(GLES20.GL_TEXTURE_2D);
	            gl.glGenTextures(1, TextureString,0);
	            textureId= TextureString[0];
	            Log.e("textureId", String.valueOf(textureId));
	            gl.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, 
	            		GLES20.GL_CLAMP_TO_EDGE); 
	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, 
	            		GLES20.GL_CLAMP_TO_EDGE); 
	            GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
	            GL2JNILib.setTextures(TextureString);
	           // GL2JNILib.setTextures(textureId);
	            bitmap.recycle();
            }

        }
        
        private Bitmap getBitmap(Context context,int resId)
        {
        	//getBitmap by decodeResources()
//        	BitmapFactory.Options options = new BitmapFactory.Options();
//        	options.inScaled = false;
//        	return BitmapFactory.decodeResource(context.getResources(), resId,options);
        
        	//getBitmap by decodeStream()
        	InputStream bitmapStream = null;
        	bitmapStream = context.getResources().openRawResource(R.drawable.bac);
        	return BitmapFactory.decodeStream(bitmapStream);
        	//经验证上面两种方法都能够
        }
    }

由于这部分之前一直有问题，纹理试过一直闪烁，一直黑色。改动了非常多地方，也不确定那些才是导致问题的根本原因，可是我尽可能贴出来。大家也多交流交流：

1.图片格式要是2的倍数*2的倍数，并且有的说不超过1024有点不超过512。做測试还是用256*256的好了。

2.

gl.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);

要在

	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, 
	            		GLES20.GL_CLAMP_TO_EDGE); 
	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, 
	            		GLES20.GL_CLAMP_TO_EDGE); 

之前

3.

	            gl.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, 
	            		GLES20.GL_CLAMP_TO_EDGE); 

最后的參数要是

GLES20.GL_CLAMP_TO_EDGE

貌似跟mipmap有关

4.

GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);

这个一定要放最后

5.

GL2JNILib.setTextures(TextureString);

传给C++层的參数一定要是int数组

接着是c++层的代码

首先是脚本改动

static const char gVertexShader[] = 
    "attribute vec4 vPosition;
"
	"attribute vec2 vTexCoords;
"
	"varying vec2 colorVarying;
"
    "void main() {
"
    "  gl_Position = vPosition;
"
	"  colorVarying = vTexCoords;
"
    "}
";

static const char gFragmentShader[] = 
	"precision mediump float;
"
	"varying vec2 colorVarying;
"
	"uniform sampler2D sampler;
"
    "void main() {
"
    "  //gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
"
	"gl_FragColor = texture2D(sampler,colorVarying);
"
    "}
";

加入了定点纹理坐标和传递给pixelShader变量

pixelShader加入了接收vertexShader传过来的參数

bool setupGraphics(int w, int h)的改动

GLuint gProgram;
GLuint gvPositionHandle;
GLuint gvTexCoorHandle;

bool setupGraphics(int w, int h) {
    printGLString("Version", GL_VERSION);
    printGLString("Vendor", GL_VENDOR);
    printGLString("Renderer", GL_RENDERER);
    printGLString("Extensions", GL_EXTENSIONS);

    LOGI("setupGraphics(%d, %d)", w, h);
    gProgram = createProgram(gVertexShader, gFragmentShader);
    if (!gProgram) {
        LOGE("Could not create program.");
        return false;
    }
    gvPositionHandle = glGetAttribLocation(gProgram, "vPosition");
    checkGlError("glGetAttribLocation");
    LOGI("glGetAttribLocation("vPosition") = %d
",
            gvPositionHandle);
    gvTexCoorHandle = glGetAttribLocation(gProgram, "vTexCoords");
    checkGlError("glGetAttribLocation");
    LOGI("glGetAttribLocation("vTexCoords") = %d
",
    		gvTexCoorHandle);

    glViewport(0, 0, w, h);
    checkGlError("glViewport");
    return true;
}

加入了

gvTexCoorHandle = glGetAttribLocation(gProgram, "vTexCoords");

获取纹理坐标属性引用id

void renderFrame() 的改动

const GLfloat gTriangleVertices[] = { 0.0f, 0.5f, -0.5f, -0.5f,
        0.5f, -0.5f };
const GLfloat gTexCoor[] = { 0.5f,0, 0,1,
		1,1 };
void renderFrame() {
    static float grey;
    grey += 0.01f;
    if (grey > 1.0f) {
        grey = 0.0f;
    }
    glClearColor(grey, grey, grey, 1.0f);
    checkGlError("glClearColor");
    glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
    //glClear( GL_STENCIL_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
    checkGlError("glClear");

    glUseProgram(gProgram);
    checkGlError("glUseProgram");

    glVertexAttribPointer(gvPositionHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices);
    checkGlError("glVertexAttribPointer");
    glVertexAttribPointer(gvTexCoorHandle, 2, GL_FLOAT, GL_FALSE, 0, gTexCoor);
    checkGlError("glVertexAttribPointer");
    glEnableVertexAttribArray(gvPositionHandle);
    checkGlError("glEnableVertexAttribArray");
    glEnableVertexAttribArray(gvTexCoorHandle);
    checkGlError("glEnableVertexAttribArray");
    glActiveTexture(GL_TEXTURE0);
    checkGlError("glActiveTexture");
    glBindTexture(GL_TEXTURE_2D,mTexture[0]);
    checkGlError("glBindTexture");
    glDrawArrays(GL_TRIANGLES, 0, 3);
    checkGlError("glDrawArrays");
}

加入了纹理坐标的数据，绑定纹理，最后画带有纹理的三角形

加入接收Java层传递过来的纹理id

JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_setTextures(JNIEnv * env, jobject obj,jintArray texture)
{
	mTexture = (GLuint *)env->GetIntArrayElements(texture,0);
//	m_texture = (unsigned int)env->GetIntArrayElements(texture,0);//it doesnt work!!!!what the fuck dont try this anymore!!!
//    const char *v = (const char *) m_texture;
//    LOGI("GL %s = %s
", "m_texture:", v);
//    v = (const char *) mTexture;
//    LOGI("GL %s = %s
", "mTexture:", v);
}

这里有个问题就是导致后面黑色纹理的主要原因：

接收Java传过来的id时要用GLuint*类型。这样在上面

<pre name="code" class="cpp"> glBindTexture(GL_TEXTURE_2D,mTexture[0]);

传进去才不会错。

都怪我c++基础不好...

最后希望大家能多点分享。像我这样刚接触OpenGL特别是在ndk上真的太少资料

项目下载链接：

http://download.csdn.net/detail/chrisfxs/7547637