android ndk调用OpenGL 实现纹理贴图Texture
首先必须说，国内在OpenGL这方面特别是ndk上的分享太太太少
这中间遇到很多问题，而这些问题需要在书上，在网上，在各种资料上找，而且书上是java层调用，网上的缺少各种文件案例，只有在java层研究，在各种案例中找需要的知识点，遇到问题最终只有google搜外国网站才能解决。
顺便说下，虽然现在google被墙，除了翻墙还有个很简单的办法上google。
http://www.gfsoso.com/
谷粉搜搜
接下来正文
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学习ndk应该都是从google配有的案例开始的吧：GL2JNIActivity
这个案例就是一个会变颜色的背景加一个绿色三角形
因为我开始学习纹理贴图，所以打算将三角形换成贴图
首先需要配置纹理
在GL2JNIView.java中修改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可以
}
}
因为这部分之前一直有问题，纹理试过一直闪烁，一直黑色，修改了很多地方，也不确定那些才是导致问题的根本原因，但是我尽可能贴出来，大家也多交流交流：
1.图片格式要是2的倍数*2的倍数，而且有的说不超过1024有点不超过512，做测试还是用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);
最后的参数要是
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++层的参数一定要是int数组
接着是c++层的代码
首先是脚本修改
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);
"
"}
";
添加了定点纹理坐标和传递给pixelShader变量
pixelShader添加了接收vertexShader传过来的参数
bool setupGraphics(int w, int h)的修改
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;
}
添加了
gvTexCoorHandle = glGetAttribLocation(gProgram, "vTexCoords");
获取纹理坐标属性引用id
void renderFrame() 的修改
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");
}
添加了纹理坐标的数据，绑定纹理，最后画带有纹理的三角形
添加接收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