OpenGL ES在android上画一个正方形
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【中文标题】OpenGL ES在android上画一个正方形【英文标题】：OpenGL ES draw a square on android 【发布时间】：2021-04-04 20:28:24 【问题描述】：我尝试在 OpenGL ES 中为 android 绘制一个正方形，但由于某种原因，我的代码崩溃了，或者只显示了 clearColor。我敢肯定，带有渲染器和 GLSurfaceView 类的项目设置是正确的，并且从文件导入顶点和片段着色器的功能有效。这是绘制正方形的代码（构造函数在我的渲染器类的 onDrawFrame 方法的 draw 方法中调用 onSurfaceCreated）：
import android.content.Context;
import android.opengl.GLES20;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.FloatBuffer;
import java.nio.IntBuffer;
public class Square
int ShaderProgramID;
private FloatBuffer vertexBuffer;
private int vertexBufferID;
private int vertexCount;
private int vertexStride;
static final int COORDS_PER_VERTEX = 3;
static final int COLORS_PER_VERTEX = 4;
static final int SIZE_OF_FLOAT = 4;
static final float coords[] =
//x: y: z: r: g: b: a:
-0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,
-0.5f,-0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f,
0.5f,-0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,
0.5f,-0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f,
0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f,
;
public Square(Context context)
String vertexShaderSrc = ReadFromfile("defaultVertexShader.glsl", context);
String fragmentShaderSrc = ReadFromfile("defaultFragmentShader.glsl", context);
int vertexID = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
GLES20.glShaderSource(vertexID, vertexShaderSrc);
GLES20.glCompileShader(vertexID);
int fragmetID = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);
GLES20.glShaderSource(fragmetID, fragmentShaderSrc);
GLES20.glCompileShader(fragmetID);
ShaderProgramID = GLES20.glCreateProgram();
GLES20.glAttachShader(ShaderProgramID, vertexID);
GLES20.glAttachShader(ShaderProgramID, fragmetID);
GLES20.glBindAttribLocation(ShaderProgramID, 0, "aPos");
GLES20.glBindAttribLocation(ShaderProgramID, 1, "aColor");
GLES20.glLinkProgram(ShaderProgramID);
positionHandle = GLES20.glGetAttribLocation(ShaderProgramID, "a_Position");
colorHandle = GLES20.glGetAttribLocation(ShaderProgramID, "a_Color");
vertexBuffer = FloatBuffer.allocate(coords.length);
vertexBuffer.put(coords);
vertexBuffer.position(0);
IntBuffer buffer = IntBuffer.allocate(1);
GLES20.glGenBuffers(1, buffer);
vertexBufferID = buffer.get(0);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vertexBufferID);
GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, coords.length * 4, vertexBuffer, GLES20.GL_STATIC_DRAW);
vertexCount = coords.length / (COORDS_PER_VERTEX + COLORS_PER_VERTEX);
vertexStride = (COORDS_PER_VERTEX + COLORS_PER_VERTEX) * 4;
private int positionHandle;
private int colorHandle;
public void draw()
GLES20.glUseProgram(ShaderProgramID);
vertexBuffer.position(0);
GLES20.glVertexAttribPointer(positionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);
GLES20.glEnableVertexAttribArray(positionHandle);
vertexBuffer.position(3);
GLES20.glVertexAttribPointer(colorHandle, COLORS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);
GLES20.glEnableVertexAttribArray(colorHandle);
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 6);
GLES20.glDisableVertexAttribArray(positionHandle);
GLES20.glDisableVertexAttribArray(colorHandle);
public String ReadFromfile(String fileName, Context context)
StringBuilder ReturnString = new StringBuilder();
InputStream fIn = null;
InputStreamReader isr = null;
BufferedReader input = null;
try
fIn = context.getResources().getAssets()
.open(fileName);
isr = new InputStreamReader(fIn);
input = new BufferedReader(isr);
String line = "";
while ((line = input.readLine()) != null)
ReturnString.append(line + "\n");
catch (Exception e)
e.getMessage();
finally
try
if (isr != null)
isr.close();
if (fIn != null)
fIn.close();
if (input != null)
input.close();
catch (Exception e2)
e2.getMessage();
return ReturnString.toString();
这是 VertexShaderCode：
attribute vec4 aPos;
attribute vec4 aColor;
varying vec4 v_Color;
void main()
v_Color = a_Color;
gl_Position = a_Position;
这是 FragmentShaderCode
precision mediump float;
varying vec4 v_Color;
void main()
gl_FragColor = v_Color;
【问题讨论】：
【参考方案1】：在顶点着色器中：
attribute vec4 aPos;
position 是 4 分量向量，但在“vertexBuffer”中位置写为 3 分量向量。所以尝试改进着色器：
attribute vec3 aPos;
也使用了“a_Position”，但未在任何地方声明，请这样做：
gl_Position = vec4(a_Pos,1.0);
并在这里改进：
positionHandle = GLES20.glGetAttribLocation(ShaderProgramID, "a_Pos");
此代码可以显示着色器是否编译，以及错误。
int[] compiled = new int[1];
GLES31.glGetShaderiv(shader, GLES31.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0)
GLES31.glDeleteShader(shader);
throw new RuntimeException("Could not compile program: "
+ GLES31.glGetShaderInfoLog(shader) + " | ");
这是准备浮动缓冲区的正确方法：
ByteBuffer bb = ByteBuffer.allocateDirect(coords.length*4);
bb.order(ByteOrder.nativeOrder());
FloatBuffer vertexBuffer = bb.asFloatBuffer();
【讨论】：
顶点现在看起来像这样：attribute vec3 aPos;属性 vec4 aColor;不同的 vec4 vColor； void main() v_Color = aColor; gl_Position = aPos; 但它仍然崩溃。我也确保在代码中的任何地方只使用 aPos 和 aColor 而不是 a_Pos 或 a_Color gl_Position = vec4(a_Pos,1.0); 我修复了所有错误，现在着色器编译成功，但应用程序仍然崩溃 哪一行崩溃了？ 第 76 行：GLES20.glVertexAttribPointer(positionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);【参考方案2】：这是当前代码：
import android.content.Context;
import android.opengl.GLES20;
import android.opengl.GLES31;
import android.util.Log;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.FloatBuffer;
import java.nio.IntBuffer;
public class Square
int ShaderProgramID;
private FloatBuffer vertexBuffer;
private int vertexBufferID;
private int vertexCount;
private int vertexStride;
static final int COORDS_PER_VERTEX = 3;
static final int COLORS_PER_VERTEX = 4;
static final int SIZE_OF_FLOAT = 4;
static final float coords[] =
//x: y: z: r: g: b: a:
-0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,
-0.5f,-0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f,
0.5f,-0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,
0.5f,-0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f,
0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f,
;
public Square(Context context)
String vertexShaderSrc = ReadFromfile("defaultVertexShader.glsl", context);
String fragmentShaderSrc = ReadFromfile("defaultFragmentShader.glsl", context);
int vertexID = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
GLES20.glShaderSource(vertexID, vertexShaderSrc);
GLES20.glCompileShader(vertexID);
int fragmetID = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);
GLES20.glShaderSource(fragmetID, fragmentShaderSrc);
GLES20.glCompileShader(fragmetID);
ShaderProgramID = GLES20.glCreateProgram();
GLES20.glAttachShader(ShaderProgramID, vertexID);
GLES20.glAttachShader(ShaderProgramID, fragmetID);
GLES20.glBindAttribLocation(ShaderProgramID, 0, "aPos");
GLES20.glBindAttribLocation(ShaderProgramID, 1, "aColor");
GLES20.glLinkProgram(ShaderProgramID);
positionHandle = GLES20.glGetAttribLocation(ShaderProgramID, "aPos");
colorHandle = GLES20.glGetAttribLocation(ShaderProgramID, "aColor");
vertexBuffer = FloatBuffer.allocate(coords.length);
vertexBuffer.put(coords);
vertexBuffer.position(0);
IntBuffer buffer = IntBuffer.allocate(1);
GLES20.glGenBuffers(1, buffer);
vertexBufferID = buffer.get(0);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vertexBufferID);
GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, coords.length * 4, vertexBuffer, GLES20.GL_STATIC_DRAW);
vertexCount = coords.length / (COORDS_PER_VERTEX + COLORS_PER_VERTEX);
vertexStride = (COORDS_PER_VERTEX + COLORS_PER_VERTEX) * 4;
private int positionHandle;
private int colorHandle;
public void draw()
GLES20.glUseProgram(ShaderProgramID);
vertexBuffer.position(0);
GLES20.glVertexAttribPointer(positionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, 0);
GLES20.glEnableVertexAttribArray(positionHandle);
vertexBuffer.position(3);
GLES20.glVertexAttribPointer(colorHandle, COLORS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, 3);
GLES20.glEnableVertexAttribArray(colorHandle);
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 6);
GLES20.glDisableVertexAttribArray(positionHandle);
GLES20.glDisableVertexAttribArray(colorHandle);
public String ReadFromfile(String fileName, Context context)
StringBuilder ReturnString = new StringBuilder();
InputStream fIn = null;
InputStreamReader isr = null;
BufferedReader input = null;
try
fIn = context.getResources().getAssets()
.open(fileName);
isr = new InputStreamReader(fIn);
input = new BufferedReader(isr);
String line = "";
while ((line = input.readLine()) != null)
ReturnString.append(line + "\n");
catch (Exception e)
e.getMessage();
finally
try
if (isr != null)
isr.close();
if (fIn != null)
fIn.close();
if (input != null)
input.close();
catch (Exception e2)
e2.getMessage();
return ReturnString.toString();
片段：
#version 310 es
precision mediump float;
in vec4 vColor;
void main()
gl_FragColor = vColor;
顶点：
#version 310 es
attribute vec3 aPos;
attribute vec4 aColor;
out vec4 vColor;
void main()
vColor = aColor;
gl_Position = vec4(aPos,1.0);
【讨论】：
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