据我了解，从 GLES30 开始，不再有 gl_FragColor 缓冲区(我看到了 HERE)
既然我无法读取“特殊变量”，我该如何读取“输出”缓冲区？
这是我的代码:
private static final String FRAGMENT_SHADER =
"#version 300 es\n"+
"#extension GL_OES_EGL_image_external_essl3 : require\n" +
"precision mediump float;\n" + // highp here doesn't seem to matter
"in vec2 vTextureCoord;\n" +
"uniform sampler2D sTexture;\n" +
"out vec4 fragColor ;\n" +
"void main() {\n" +
" vec4 tc = texture(sTexture, vTextureCoord);\n" +
" fragColor.r = tc.r * 0.3 + tc.g * 0.59 + tc.b * 0.11;\n" +
" fragColor.g = tc.r * 0.3 + tc.g * 0.59 + tc.b * 0.11;\n" +
" fragColor.b = tc.r * 0.3 + tc.g * 0.59 + tc.b * 0.11;\n" +
"}\n";
这里我尝试读取数据:
ByteBuffer mPixelBuf = ByteBuffer.allocateDirect(mWidth * mHeight * 4);
mPixelBuf.order(ByteOrder.LITTLE_ENDIAN);
GLES30.glReadPixels(startX, startY, frameWidth, frameHeight, GLES30.GL_RGBA, GLES30.GL_UNSIGNED_BYTE, mPixelBuf);
代码中没有gl错误。
输出 mPixelBuf 只有零。
如何确保 fragColor 正在读取？
谢谢
Update1-全纹理渲染代码:
package com.MES.YOtm.AnalyzingAdapter;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import android.graphics.SurfaceTexture;
import android.opengl.GLES11Ext;
import android.opengl.GLES30;
import android.opengl.Matrix;
import android.util.Log;
/**
* Code for rendering a texture onto a surface using OpenGL ES 2.0.
*/
public class STextureRender {
private static final String TAG = "Myopengl";
private int zoom;
private static final int FLOAT_SIZE_BYTES = 4;
private static final int TRIANGLE_VERTICES_DATA_STRIDE_BYTES = 5 * FLOAT_SIZE_BYTES;
private static final int TRIANGLE_VERTICES_DATA_POS_OFFSET = 0;
private static final int TRIANGLE_VERTICES_DATA_UV_OFFSET = 3;
private final float[] mTriangleVerticesData = {
// X, Y, Z, U, V
-1.0f, -1.0f, 0, 0.f, 0.f,
1.0f, -1.0f, 0, 1.f, 0.f,
-1.0f, 1.0f, 0, 0.f, 1.f,
1.0f, 1.0f, 0, 1.f, 1.f,
};
private FloatBuffer mTriangleVertices;
private static final String VERTEX_SHADER =
"#version 300 es\n"+
"uniform mat4 uMVPMatrix;\n" +
"uniform mat4 uSTMatrix;\n" +
"in vec4 aPosition;\n" +
"in vec4 aTextureCoord;\n" +
"out vec2 vTextureCoord;\n" +
"void main() {\n" +
" gl_Position = uMVPMatrix * aPosition;\n" +
" vTextureCoord = (uSTMatrix * aTextureCoord).xy;\n" +
"}\n";
//Smapler2D
private static final String FRAGMENT_SHADER =
"#version 300 es\n"+
"#extension GL_OES_EGL_image_external_essl3 : require\n" +
"precision mediump float;\n" + // highp here doesn't seem to matter
"in vec2 vTextureCoord;\n" +
"uniform mediump sampler2D sTexture;\n" +
"layout(location = 0) out mediump vec4 fragColor ;\n" +
"void main() {\n" +
" vec4 tc = texture(sTexture, vTextureCoord);\n" +
" fragColor.r = tc.r * 0.3 + tc.g * 0.59 + tc.b * 0.11;\n" +
" fragColor.g = tc.r * 0.3 + tc.g * 0.59 + tc.b * 0.11;\n" +
" fragColor.b = tc.r * 0.3 + tc.g * 0.59 + tc.b * 0.11;\n" +
"}\n";
private float[] mMVPMatrix = new float[16];
private float[] mSTMatrix = new float[16];
private int mProgram;
private int mTextureID = -12345;
private int muMVPMatrixHandle;
private int muSTMatrixHandle;
private int maPositionHandle;
private int maTextureHandle;
public STextureRender(int _zoom) {
Log.v("My Error", "Start STextureRender constructor");
try
{
mTriangleVertices = ByteBuffer.allocateDirect(
mTriangleVerticesData.length * FLOAT_SIZE_BYTES)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mTriangleVertices.put(mTriangleVerticesData).position(0);
Matrix.setIdentityM(mSTMatrix, 0);
zoom = _zoom;
}
catch(Exception ex)
{
Log.v("My Error", "STextureRender Error = " + ex.toString());
}
Log.v("My Error", "End STextureRender constructor");
}
public int getTextureId() {
return mTextureID;
}
/**
* Draws the external texture in SurfaceTexture onto the current EGL surface.
*/
public void drawFrame(SurfaceTexture st, boolean invert) {
checkGlError("onDrawFrame start");
try
{
st.getTransformMatrix(mSTMatrix);
if (invert) {
mSTMatrix[5] = -mSTMatrix[5];
mSTMatrix[13] = 1.0f - mSTMatrix[13];
}
GLES30.glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
GLES30.glClear(GLES30.GL_COLOR_BUFFER_BIT);
GLES30.glUseProgram(mProgram);
checkGlError("glUseProgram");
GLES30.glActiveTexture(GLES30.GL_TEXTURE0);
GLES30.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, mTextureID);
mTriangleVertices.position(TRIANGLE_VERTICES_DATA_POS_OFFSET);
GLES30.glVertexAttribPointer(maPositionHandle, 3, GLES30.GL_FLOAT, false,
TRIANGLE_VERTICES_DATA_STRIDE_BYTES, mTriangleVertices);
checkGlError("glVertexAttribPointer maPosition");
GLES30.glEnableVertexAttribArray(maPositionHandle);
checkGlError("glEnableVertexAttribArray maPositionHandle");
mTriangleVertices.position(TRIANGLE_VERTICES_DATA_UV_OFFSET);
GLES30.glVertexAttribPointer(maTextureHandle, 2, GLES30.GL_FLOAT, false,
TRIANGLE_VERTICES_DATA_STRIDE_BYTES, mTriangleVertices);
checkGlError("glVertexAttribPointer maTextureHandle");
GLES30.glEnableVertexAttribArray(maTextureHandle);
checkGlError("glEnableVertexAttribArray maTextureHandle");
Matrix.setIdentityM(mMVPMatrix, 0);
GLES30.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mMVPMatrix, 0);
GLES30.glUniformMatrix4fv(muSTMatrixHandle, 1, false, mSTMatrix, 0);
GLES30.glDrawArrays(GLES30.GL_TRIANGLE_STRIP, 0, 4);
checkGlError("glDrawArrays");
}
catch(Exception ex)
{
Log.v("My Error", "drawFrame Error = " + ex.toString());
}
}
/**
* Initializes GL state. Call this after the EGL surface has been created and made current.
*/
public void surfaceCreated() {
try
{
mProgram = createProgram(VERTEX_SHADER, FRAGMENT_SHADER);
if (mProgram == 0) {
throw new RuntimeException("failed creating program");
}
maPositionHandle = GLES30.glGetAttribLocation(mProgram, "aPosition");
checkGlError("glGetAttribLocation aPosition");
if (maPositionHandle == -1) {
throw new RuntimeException("Could not get attrib location for aPosition");
}
maTextureHandle = GLES30.glGetAttribLocation(mProgram, "aTextureCoord");
checkGlError("glGetAttribLocation aTextureCoord");
if (maTextureHandle == -1) {
throw new RuntimeException("Could not get attrib location for aTextureCoord");
}
muMVPMatrixHandle = GLES30.glGetUniformLocation(mProgram, "uMVPMatrix");
checkGlError("glGetUniformLocation uMVPMatrix");
if (muMVPMatrixHandle == -1) {
throw new RuntimeException("Could not get attrib location for uMVPMatrix");
}
muSTMatrixHandle = GLES30.glGetUniformLocation(mProgram, "uSTMatrix");
checkGlError("glGetUniformLocation uSTMatrix");
if (muSTMatrixHandle == -1) {
throw new RuntimeException("Could not get attrib location for uSTMatrix");
}
int[] textures = new int[1];
GLES30.glGenTextures(1, textures, 0);
mTextureID = textures[0];
GLES30.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, mTextureID);
checkGlError("glBindTexture mTextureID");
GLES30.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES30.GL_TEXTURE_MIN_FILTER,
GLES30.GL_NEAREST);
GLES30.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES30.GL_TEXTURE_MAG_FILTER,
GLES30.GL_LINEAR);
GLES30.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES30.GL_TEXTURE_WRAP_S,
GLES30.GL_CLAMP_TO_EDGE);
GLES30.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES30.GL_TEXTURE_WRAP_T,
GLES30.GL_CLAMP_TO_EDGE);
checkGlError("glTexParameter");
}
catch(Exception ex)
{
Log.v("My Error", "surfaceCreated Error = " + ex.toString());
}
}
/**
* Replaces the fragment shader. Pass in null to reset to default.
*/
public void changementShader(String fragmentShader) {
try
{
if (fragmentShader == null) {
fragmentShader = FRAGMENT_SHADER;
}
GLES30.glDeleteProgram(mProgram);
mProgram = createProgram(VERTEX_SHADER, fragmentShader);
if (mProgram == 0) {
Log.v("My Error", "failed creating program");
throw new RuntimeException("failed creating program");
}
}
catch(Exception ex)
{
Log.v("My Error", " changementShader Error = " + ex.toString());
}
}
private int loadShader(int shaderType, String source) {
try
{
int shader = GLES30.glCreateShader(shaderType);
checkGlError("glCreateShader type=" + shaderType);
GLES30.glShaderSource(shader, source);
GLES30.glCompileShader(shader);
int[] compiled = new int[1];
GLES30.glGetShaderiv(shader, GLES30.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0) {
Log.e(TAG, "Could not compile shader " + shaderType + ":");
Log.e(TAG, " " + GLES30.glGetShaderInfoLog(shader));
GLES30.glDeleteShader(shader);
shader = 0;
}
return shader;
}
catch(Exception ex)
{
Log.v("My Error", "loadShader Error = " + ex.toString());
return 0;
}
}
private int createProgram(String vertexSource, String fragmentSource) {
try
{
int vertexShader = loadShader(GLES30.GL_VERTEX_SHADER, vertexSource);
if (vertexShader == 0) {
return 0;
}
int pixelShader = loadShader(GLES30.GL_FRAGMENT_SHADER, fragmentSource);
if (pixelShader == 0) {
return 0;
}
int program = GLES30.glCreateProgram();
checkGlError("glCreateProgram");
if (program == 0) {
Log.e(TAG, "Could not create program");
}
GLES30.glAttachShader(program, vertexShader);
checkGlError("glAttachShader");
GLES30.glAttachShader(program, pixelShader);
checkGlError("glAttachShader");
GLES30.glLinkProgram(program);
int[] linkStatus = new int[1];
GLES30.glGetProgramiv(program, GLES30.GL_LINK_STATUS, linkStatus, 0);
if (linkStatus[0] != GLES30.GL_TRUE) {
Log.e(TAG, "Could not link program: ");
Log.e(TAG, GLES30.glGetProgramInfoLog(program));
GLES30.glDeleteProgram(program);
program = 0;
}
return program;
}
catch(Exception ex)
{
Log.v("My Error", "createProgram Error = " + ex.toString());
return 0;
}
}
public void checkGlError(String op) {
int error;
while ((error = GLES30.glGetError()) != GLES30.GL_NO_ERROR) {
Log.e(TAG, op + ": glError " + error);
throw new RuntimeException(op + ": glError " + error);
}
}
}
最佳答案
您的着色器代码与 glReadPixels 读取的内容完全无关，也与特殊变量名无关。它从当前绑定(bind)的读取帧缓冲区中读取；即 glReadPixels 在 ES 3.0 中的工作方式与它在 ES 2.0 中的工作方式完全相同。
唯一的异常(exception)是多渲染目标支持，但这与本例无关。
How can I make sure that fragColor is reading?
glClearColor(some interesting color)
glClear(COLOR_BUFFER_BIT)
glReadPixels()
assert color == some interesting color
关于android - 如何在 Android 上使用基于 GLES30 的 glreadpixels 从特定缓冲区读取数据，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39506470/