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我進入了開放式gl 2.0（在android上），我很困惑，因爲我在this video（在1:11:05）聽說所有3中顯示的座標系統範圍從-1到1如果我使用座標（（-1 | -1 | 0），（0 | 1 | 0），（1 | 0 | 0）），但它們似乎範圍在-2到2之間，我得到一個三角形只有一半，因爲我希望它是一樣大：爲什麼我的OpenGL座標系統軸[-1; 1]？
我asumption是，座標系統不正確時，莫名其妙地縮放，因爲如果我加倍的座標爲（（ - 2 | -2 | 0），（0 | 2 | 0），（2 | 0 | 0）），我得到了我的前例pected擺在首位：
爲什麼會出現這種情況，我怎麼可以使用第一組座標時解決它，讓我得到三角比例在整個屏幕（如第二個圖） （（-1 | -1 | 0），（0 | 1 | 0），（1 | 0 | 0））？
代碼：
活動XML：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="simonlammer.htlleonding.ac.at.openglcameraoverlay.MainActivity">
<simonlammer.htlleonding.ac.at.openglcameraoverlay.GlOverlay
android:id="@+id/overlay"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
MainActivity：
public class MainActivity extends AppCompatActivity {
private GlOverlay glOverlay;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
glOverlay = (GlOverlay) findViewById(R.id.overlay);
}
@Override
protected void onPause() {
glOverlay.onPause();
super.onPause();
}
@Override
protected void onResume() {
super.onResume();
glOverlay.onResume();
}
}
GlOverlay：
public class GlOverlay extends GLSurfaceView {
private GlEs20Renderer renderer;
public GlOverlay(Context context) {
super(context);
init();
}
public GlOverlay(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
this.renderer = new GlEs20Renderer();
this.setEGLContextClientVersion(2);
this.setRenderer(renderer);
this.setRenderMode(RENDERMODE_CONTINUOUSLY);
}
}
GlEs20渲染器：
public class GlEs20Renderer implements GLSurfaceView.Renderer {
private static final int COORDS_PER_VERTEX = 4;
private final float[] triangleCoords = {
-1.0f, -1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f
};
private final int vertexCount = triangleCoords.length/COORDS_PER_VERTEX;
private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per float
private FloatBuffer vertexBuffer;
private boolean setup = false;
private int program = -1;
private void setup() {
vertexBuffer = ByteBuffer.allocateDirect(triangleCoords.length * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
vertexBuffer.put(triangleCoords);
vertexBuffer.position(0);
String vertexShaderSource =
"attribute vec4 vPosition;" +
"uniform vec4 vTranslate;" +
"void main() {" +
" gl_Position = vPosition + vTranslate;" +
"}";
String fragmentShaderSource =
"precision mediump float;" +
"uniform vec4 vColor;" +
"void main() {" +
" gl_FragColor = vColor;" +
"}";
int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER,
vertexShaderSource);
int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER,
fragmentShaderSource);
// create empty OpenGL ES Program
program = GLES20.glCreateProgram();
// add the vertex shader to program
GLES20.glAttachShader(program, vertexShader);
// add the fragment shader to program
GLES20.glAttachShader(program, fragmentShader);
// creates OpenGL ES program executables
GLES20.glLinkProgram(program);
}
private static int loadShader(int type, String shaderCode){
// create a vertex shader type (GLES20.GL_VERTEX_SHADER)
// or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
int shader = GLES20.glCreateShader(type);
// add the source code to the shader and compile it
GLES20.glShaderSource(shader, shaderCode);
GLES20.glCompileShader(shader);
return shader;
}
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
}
@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
}
@Override
public void onDrawFrame(GL10 gl) {
if (!setup) {
setup();
setup = true;
}
GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
// Add program to OpenGL ES environment
GLES20.glUseProgram(program);
// get handle to vertex shader's vPosition member
int mPositionHandle = GLES20.glGetAttribLocation(program, "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);
// get handle to fragment shader's vColor member
int mColorHandle = GLES20.glGetUniformLocation(program, "vColor");
// Set color for drawing the triangle
GLES20.glUniform4fv(mColorHandle, 1, new float[] {0.5f, 0.0f, 0.0f, 1.0f}, 0);
// move
GLES20.glUniform4fv(GLES20.glGetUniformLocation(program, "vTranslate"), 1, new float[] {0f, 0f, 0f, 1f}, 0);
// Draw the triangle
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);
// Disable vertex array
GLES20.glDisableVertexAttribArray(mPositionHandle);
}
}
該代碼在github上可用：https：//github.com/SimonLammer/Android-GlEs20CameraOverlay – EvilDevil
我開始了一個新的分支，其中我刪除了與此問題無關的所有代碼：https：//github.com/SimonLammer/Android的GlEs20CameraOverlay /樹/不帶攝像頭預覽 – EvilDevil