为什么它不是一个立方体？
问题描述：
我正在研究一个简单的项目，它可以在OpenGLES 2.0 android 4.1中创建一个立方体并旋转它。但绘制的形状不应该是t cube. and it is rotating a axis that i wasn。我想它会在相机空间旋转X，Y轴。所以谢谢你的建议。为什么它不是一个立方体？
public float mAngleX;
public float mAngleY;
private Quadrat quad;
private final float[] MVPMatrix = new float[16];
private final float[] projectionMatrix = new float[16];
private final float[] mVMatrix = new float[16];
private final float[] rotationMatrix = new float[16];
public MyRenderer(){
mAngleX = 0;
mAngleY = 0;
}
// @Override
public void onSurfaceCreated(GL10 unused, EGLConfig config){
// Set the background frame color
GLES20.glClearColor(0.5f, 0.2f, 0.1f, 1.0f);
Matrix.setLookAtM(mVMatrix, 0, 0.0f, 0.0f, -5.0f, 0f, 0f, 1f, 0f, 1.0f, 0.0f);
quad = new Quadrat();
}
// @Override
public void onSurfaceChanged(GL10 unused, int width, int height){
GLES20.glViewport(0, 0, width, height);
float ratio = (float) width/height;
Matrix.perspectiveM(projectionMatrix, 0, 45.0f, ratio, 1, 9);
}
//@Override
public void onDrawFrame(GL10 unused) {
// Draw background color
GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
Matrix.setRotateM(rotationMatrix, 0, mAngleX, 0.0f, 1.0f, 0.0f);
Matrix.multiplyMM(MVPMatrix, 0, rotationMatrix, 0, MVPMatrix, 0);
Matrix.setRotateM(rotationMatrix, 0, mAngleY, 1.0f, 0.0f, 0.0f);
Matrix.multiplyMM(MVPMatrix, 0, rotationMatrix, 0, MVPMatrix, 0);
Matrix.multiplyMM(MVPMatrix, 0, projectionMatrix, 0, mVMatrix, 0);
quad.draw(MVPMatrix, mVMatrix);
}
public static int loadShader(int type, String shaderCode){
int shader = GLES20.glCreateShader(type);
// add the source code to the shader and compile it
GLES20.glShaderSource(shader, shaderCode);
GLES20.glCompileShader(shader);
return shader;
}
}
并且样方类在下面。
class Quadrat {
private final String vertexShaderCode =
"uniform mat4 uMVPMatrix;\n" +
"uniform mat4 uMVMatrix;\n" +
"uniform vec3 uLightPos;\n" +
"attribute vec4 aPosition;\n" +
"attribute vec4 aColor;\n" +
"attribute vec4 aNormal;\n" +
"varying vec4 vColor;\n" +
"void main() {\n" +
"gl_Position = uMVPMatrix * aPosition;\n" +
"}\n";
private final String fragmentShaderCode =
"precision mediump float;\n" +
"varying vec4 vColor;\n" +
"void main() {\n" +
"gl_FragColor = vec4(1.0, 0.9, 0.4, 1.0);\n" +
"}\n";
private final FloatBuffer vertexBuffer;
private final int mProgram;
private int mPositionHandle;
private int muMVPMatrixHandle;
private int muLightPosHandle;
private int muMVMatrixHandle;
// number of coordinates per vertex in this array
static final int COORDS_PER_VERTEX = 3;
static float quadrateCoords[] = { // in counterclockwise order:
// front
-0.5f, -0.5f, 0.5f,
0.5f, -0.5f, 0.5f,
-0.5f, 0.5f, 0.5f,
0.5f, 0.5f, 0.5f,
// back
-0.5f, -0.5f, -0.5f,
0.5f, -0.5f, -0.5f,
-0.5f, 0.5f, -0.5f,
0.5f, 0.5f, -0.5f,
// left
-0.5f, -0.5f, 0.5f,
-0.5f, -0.5f, -0.5f,
-0.5f, 0.5f, 0.5f,
-0.5f, 0.5f, -0.5f,
// right
0.5f, -0.5f, 0.5f,
0.5f, -0.5f, -0.5f,
0.5f, 0.5f, 0.5f,
0.5f, 0.5f, -0.5f,
// up
-0.5f, 0.5f, 0.5f,
0.5f, 0.5f, 0.5f,
-0.5f, 0.5f, -0.5f,
0.5f, 0.5f, -0.5f,
// bottom
-0.5f, -0.5f, 0.5f,
0.5f, -0.5f, 0.5f,
-0.5f, -0.5f, -0.5f,
0.5f, -0.5f, -0.5f
};
private final int vertexStride = COORDS_PER_VERTEX * 4; // bytes per vertex
public Quadrat() {
// initialize vertex byte buffer for shape coordinates
ByteBuffer bb = ByteBuffer.allocateDirect(quadrateCoords.length * 4);
// use the device hardware's native byte order
bb.order(ByteOrder.nativeOrder());
// create a floating point buffer from the ByteBuffer
vertexBuffer = bb.asFloatBuffer();
// add the coordinates to the FloatBuffer
vertexBuffer.put(quadrateCoords);
vertexBuffer.position(0);
// prepare shaders and OpenGL program
int vertexShader = MyRenderer.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
int fragmentShader = MyRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);
mProgram = GLES20.glCreateProgram(); // create empty OpenGL Program
GLES20.glAttachShader(mProgram, vertexShader); // add the vertex shader to program
GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
GLES20.glLinkProgram(mProgram); // create OpenGL program executables
}
public void draw(float[] mvpMatrix, float[] mVMatrix) {
// Add program to OpenGL environment
GLES20.glUseProgram(mProgram);
// get handle to vertex shader's aPosition member
mPositionHandle = GLES20.glGetAttribLocation(mProgram, "aPosition");
// Enable a handle to the triangle vertices
// Prepare the triangle coordinate data
GLES20.glEnableVertexAttribArray(mPositionHandle);
GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);
vertexStride，vertexBuffer2）;
vertexStride，vertexBuffer3）;
muMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mvpMatrix, 0);
muMVMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVMatrix");
GLES20.glUniformMatrix4fv(muMVMatrixHandle, 1, false, mVMatrix, 0);
muLightPosHandle = GLES20.glGetUniformLocation(mProgram, "uLightPos");
GLES20.glUniform3f(muLightPosHandle, 10.0f, 10.0f, 15.0f);
// Front
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
// Back
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 4, 4);
// Left
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 8, 4);
// Right
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 12, 4);
// Top
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 16, 4);
// Right
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 20, 4);
// Disable vertex array
GLES20.glDisableVertexAttribArray(mPositionHandle);
}
}
答
在
Api demos > Graphics > OpenGL ES > Touch Rotate
安装软件包Api demos和看看例子Touch Rotate您可以在
android-sdk-linux/samples/android-version/ApiDemos/
设置你的vertexStride为0，而不是4到达源代码。 – tolgap 2012-08-01 08:12:43