Java 在OpenGL ES 2.0中,如何从数组中读取4个以上的顶点数据?
我试图在OpenGL ES 2.0中从浮点数组缓冲区中为顶点位置和颜色绘制一个挨着一个的点,但每次绘制只能接受4个顶点。当我添加更多,然后告诉它绘制更多,那么它将只绘制阵列中的2个非相邻顶点。为什么会这样?为什么我不能在一个实例中绘制超过4个顶点?如果可以,怎么做Java 在OpenGL ES 2.0中,如何从数组中读取4个以上的顶点数据?,java,android,opengl-es,glsl,opengl-es-2.0,Java,Android,Opengl Es,Glsl,Opengl Es 2.0,我试图在OpenGL ES 2.0中从浮点数组缓冲区中为顶点位置和颜色绘制一个挨着一个的点,但每次绘制只能接受4个顶点。当我添加更多,然后告诉它绘制更多,那么它将只绘制阵列中的2个非相邻顶点。为什么会这样?为什么我不能在一个实例中绘制超过4个顶点?如果可以,怎么做 这里有一个例子。 当我有3*4数组数据时,它会这样绘制它们: ,这是正确完成的 例如,如果我设置3*6数组数据,它不会绘制6个点,它会绘制如下内容: 我的大部分代码都来自opengles课程项目,我仍在学习,不太了解onSurf
这里有一个例子。 当我有
3*4
数组数据时,它会这样绘制它们:
代码>,这是正确完成的
例如,如果我设置3*6
数组数据,它不会绘制6个点,它会绘制如下内容:
代码>
我的大部分代码都来自opengles
课程项目,我仍在学习,不太了解onSurfaceCreated
中的内容是如何完成的
以下是我的OpenGLRenderer类:
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
...
final String vertexShader =
"uniform mat4 u_MVPMatrix; \n" // A constant representing the combined model/view/projection matrix.
+ "attribute vec4 a_Position; \n" // Per-vertex position information we will pass in.
+ "attribute vec4 a_Color; \n" // Per-vertex color information we will pass in.
+ "varying vec4 v_Color; \n" // This will be passed into the fragment shader.
+ "void main() \n" // The entry point for our vertex shader.
+ "{ \n"
+ " v_Color = a_Color; \n" // Pass the color through to the fragment shader.
// It will be interpolated across the triangle.
+ " gl_Position = u_MVPMatrix \n" // gl_Position is a special variable used to store the final position.
+ " * a_Position; \n" // Multiply the vertex by the matrix to get the final point in
+ "} \n"; // normalized screen coordinates.
final String fragmentShader =
"precision mediump float; \n" // Set the default precision to medium. We don't need as high of a
// precision in the fragment shader.
+ "varying vec4 v_Color; \n" // This is the color from the vertex shader interpolated across the
// triangle per fragment.
+ "void main() \n" // The entry point for our fragment shader.
+ "{ \n"
+ " gl_FragColor = v_Color; \n" // Pass the color directly through the pipeline.
+ "} \n";
// Load in the vertex shader.
int vertexShaderHandle = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
if (vertexShaderHandle != 0)
{
// Pass in the shader source.
GLES20.glShaderSource(vertexShaderHandle, vertexShader);
// Compile the shader.
GLES20.glCompileShader(vertexShaderHandle);
// Get the compilation status.
final int[] compileStatus = new int[1];
GLES20.glGetShaderiv(vertexShaderHandle, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
// If the compilation failed, delete the shader.
if (compileStatus[0] == 0)
{
GLES20.glDeleteShader(vertexShaderHandle);
vertexShaderHandle = 0;
}
}
if (vertexShaderHandle == 0)
{
throw new RuntimeException("Error creating vertex shader.");
}
// Load in the fragment shader shader.
int fragmentShaderHandle = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);
if (fragmentShaderHandle != 0)
{
// Pass in the shader source.
GLES20.glShaderSource(fragmentShaderHandle, fragmentShader);
// Compile the shader.
GLES20.glCompileShader(fragmentShaderHandle);
// Get the compilation status.
final int[] compileStatus = new int[1];
GLES20.glGetShaderiv(fragmentShaderHandle, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
// If the compilation failed, delete the shader.
if (compileStatus[0] == 0)
{
GLES20.glDeleteShader(fragmentShaderHandle);
fragmentShaderHandle = 0;
}
}
if (fragmentShaderHandle == 0)
{
throw new RuntimeException("Error creating fragment shader.");
}
// Create a program object and store the handle to it.
int programHandle = GLES20.glCreateProgram();
if (programHandle != 0)
{
// Bind the vertex shader to the program.
GLES20.glAttachShader(programHandle, vertexShaderHandle);
// Bind the fragment shader to the program.
GLES20.glAttachShader(programHandle, fragmentShaderHandle);
// Bind attributes
GLES20.glBindAttribLocation(programHandle, 0, "a_Position");
GLES20.glBindAttribLocation(programHandle, 1, "a_Color");
// Link the two shaders together into a program.
GLES20.glLinkProgram(programHandle);
// Get the link status.
final int[] linkStatus = new int[1];
GLES20.glGetProgramiv(programHandle, GLES20.GL_LINK_STATUS, linkStatus, 0);
// If the link failed, delete the program.
if (linkStatus[0] == 0)
{
GLES20.glDeleteProgram(programHandle);
programHandle = 0;
}
}
if (programHandle == 0)
{
throw new RuntimeException("Error creating program.");
}
// Set program handles. These will later be used to pass in values to the program.
mMVPMatrixHandle = GLES20.glGetUniformLocation(programHandle, "u_MVPMatrix");
mPositionHandle = GLES20.glGetAttribLocation(programHandle, "a_Position");
mColorHandle = GLES20.glGetAttribLocation(programHandle, "a_Color");
// Tell OpenGL to use this program when rendering.
GLES20.glUseProgram(programHandle);
}
绘制要点:
@Override
public void onDrawFrame(GL10 gl) {
GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
Matrix.setIdentityM(mModelMatrix, 0);
drawPoints();
}
// Like I said, 4 and below works without any issue
private final int vertexesToDraw = 6;
// x, y, z (z being upwards)
private final float[] vertexPosData = {
0.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
2.0f, 0.0f, 0.0f,
3.0f, 0.0f, 0.0f,
4.0f, 0.0f, 0.0f,
5.0f, 0.0f, 0.0f
};
// red, green, blue, alpha
private final float[] vertexColorData = {
1.0f, 0.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f
};
FloatBuffer mVertexPos, mVertexColor;
// this gets initialized first
private void setupPoints() {
mVertexPos = ByteBuffer.allocateDirect(vertexPosData.length * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
mVertexPos.put(vertexPosData).position(0);
mVertexPos.position(0);
mVertexColor = ByteBuffer.allocateDirect(vertexColorData.length * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
mVertexColor.put(vertexColorData).position(0);
mVertexColor.position(0);
}
private void drawPoints() {
GLES20.glVertexAttribPointer(mPositionHandle, 3, GLES20.GL_FLOAT, false, 3 * vertexesToDraw, mVertexPos);
GLES20.glEnableVertexAttribArray(mPositionHandle);
GLES20.glVertexAttribPointer(mColorHandle, 4, GLES20.GL_FLOAT, false, 4 * vertexesToDraw, mVertexColor);
GLES20.glEnableVertexAttribArray(mColorHandle);
Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);
GLES20.glDrawArrays(GLES20.GL_POINTS, 0, vertexesToDraw);
}
的第5个参数是连续通用顶点属性(stride
)之间的字节偏移量,而不是缓冲区中的元素数
这意味着,对于类型为float(float的大小为4字节)且元组大小为3(例如x、y、z坐标)的属性,步长参数必须为4*3=12。
对于元组大小为4(RGBA颜色)的属性,步长参数必须为4*4=16
GLES20.glvertexattributepointer(mPositionHandle,3,GLES20.GL_FLOAT,false,3*4,mVertexPos);
GLES20.GlenableVertexAttributeArray(mPositionHandle);
GLES20.glvertexattributepointer(mColorHandle,4,GLES20.GL_FLOAT,false,4*4,mVertexColor);
GLES20.GlenableVertexAttributeArray(mColorHandle);
由于顶点紧密排列,因此步幅可以设置为0。这是由glvertexattributepointer
提供的特殊情况。当步幅为0时,将通过“大小和类型”参数自动计算步幅
GLES20.glvertexattributepointer(mPositionHandle,3,GLES20.GL_FLOAT,false,0,mVertexPos);
GLES20.GlenableVertexAttributeArray(mPositionHandle);
GLES20.glvertexattributepointer(mColorHandle,4,GLES20.GL_FLOAT,false,0,mVertexColor);
GLES20.GlenableVertexAttributeArray(mColorHandle);
请注意,如果有4个属性,则缓冲区中的元素数(浮点值数)将与连续通用顶点属性之间的字节偏移量一致。因此,4个顶点同时工作,但6个顶点失败。
缓冲区的大小从未明确设置。调用glDrawArrays
时,启用的顶点属性必须引用一个缓冲区,该缓冲区足够大,可以提供所需的属性。谢谢!我很高兴接受这个答案,因为它解决了我的问题。非常感谢你用这种方法总结了跨步的实际意义。在ByteBuffer.allocateDirect
方法中,乘以源数组的长度基本相同。