我最近开始使用OpenGL ES 2 for android。我按照他们的例子绘制了形状，然后我进一步创建了一个立方体。我现在正试图获得漂亮的色彩效果（每个人都面对不同的颜色）。我已经定义了一个colorBuffer，它有一个每个顶点的颜色，但是当我绘制形状时，图像是黑色的。
如果我只使用一种颜色，而不是缓冲区，则形状很好。
我尝试从positionBuffer调整我的colorBuffer，但我做错了。
这是我的代码：
public class Cube {
private FloatBuffer vertexBuffer; // Buffer for vertex-array
private final FloatBuffer colorsBuffer;
private static final int COORDS_PER_VERTEX = 3;
private static final int COORDS_PER_COLOR = 4;
private ShortBuffer drawListBuffer;
private int mColorHandle;
// float color[] = { 0.63671875f, 0.76953125f, 0.22265625f, 1.0f };
private float colors[] ={
// FRONT
1.0f, 0.5f, 0.0f, 1.0f,
1.0f, 0.5f, 0.0f, 1.0f,
1.0f, 0.5f, 0.0f, 1.0f,
1.0f, 0.5f, 0.0f, 1.0f,
//RIGHT
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
//RIGHT
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
//RIGHT
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
//RIGHT
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
//RIGHT
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
};
short[] drawOrder = {
0, 1, 2, 0, 2, 3,
4, 5, 6, 4, 6, 7,
8, 9, 10, 8, 10, 11,
12, 13, 14, 12, 14, 15,
16, 17, 18, 16, 18, 19,
20, 21, 22, 20, 22, 23,
};
private float cubeCoords[] = {
// FRONT
-1.0f, 1.0f, 1.0f, // 0. top-left-front
-1.0f, -1.0f, 1.0f, // 1. bottom-left-front
1.0f, -1.0f, 1.0f, // 2. bottom-right-front
1.0f, 1.0f, 1.0f, // 3. top-right-front
// RIGHT
1.0f, 1.0f, 1.0f, // 3. top-right-front
1.0f, -1.0f, 1.0f, // 2. bottom-right-front
1.0f, -1.0f, -1.0f, // 4. right-top-front
1.0f, 1.0f, -1.0f, // 5. right-top-back
// BACK
1.0f, 1.0f, -1.0f, // 5. right-top-back
1.0f, -1.0f, -1.0f, // 4. right-top-front
-1.0f, -1.0f, -1.0f, // 6. right-top-back
-1.0f, 1.0f, -1.0f, // 7. left-top-back
// LEFT
-1.0f, 1.0f, -1.0f, // 7. left-top-back
-1.0f, -1.0f, -1.0f, // 6. right-top-back
-1.0f, -1.0f, 1.0f, // 1. bottom-left-front
-1.0f, 1.0f, 1.0f, // 0. top-left-front
// BOTTOM
-1.0f, -1.0f, 1.0f, // 1. bottom-left-front
1.0f, -1.0f, 1.0f, // 2. bottom-right-front
1.0f, -1.0f, -1.0f, // 4. right-top-front
-1.0f, -1.0f, -1.0f, // 6. right-top-back
// TOP
-1.0f, 1.0f, 1.0f, // 0. top-left-front
1.0f, 1.0f, 1.0f, // 3. top-right-front
1.0f, 1.0f, -1.0f, // 5. right-top-back
-1.0f, 1.0f, -1.0f, // 7. left-top-back
};
private final String vertexShaderCode =
"uniform mat4 uMVPMatrix;" +
"attribute vec4 vPosition;" +
"void main() {" +
" gl_Position = uMVPMatrix * vPosition;" +
"}";
private final String fragmentShaderCode =
"precision mediump float;" +
"uniform vec4 vColor;" +
"void main() {" +
" gl_FragColor = vColor;" +
"}";
private int MVPMatrixHandle;
private int mPositionHandle;
private int colorHandle;
private final int mProgram;
private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex
private final int colorStride = COORDS_PER_COLOR * 4;
private final int vertexCount = cubeCoords.length / COORDS_PER_VERTEX;
// Constructor - Set up the buffers
public Cube() {
Log.d("TAG","vertexCount: "+vertexCount);
// Setup vertex-array buffer. Vertices in float. An float has 4 bytes
ByteBuffer vbb = ByteBuffer.allocateDirect(cubeCoords.length * 4);
vbb.order(ByteOrder.nativeOrder()); // Use native byte order
vertexBuffer = vbb.asFloatBuffer(); // Convert from byte to float
vertexBuffer.put(cubeCoords); // Copy data into buffer
vertexBuffer.position(0); // Rewind
// initialize byte buffer for the draw list
ByteBuffer dlb = ByteBuffer.allocateDirect(
// (# of coordinate values * 2 bytes per short)
drawOrder.length * 2);
dlb.order(ByteOrder.nativeOrder());
drawListBuffer = dlb.asShortBuffer();
drawListBuffer.put(drawOrder);
drawListBuffer.position(0);
colorsBuffer = ByteBuffer.allocateDirect(colors.length * 4).order(ByteOrder.nativeOrder())
.asFloatBuffer();
colorsBuffer.put(colors);
colorsBuffer.position(0);
int vertexShader = MyGLRenderer.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
int fragmentShader = MyGLRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);
mProgram = GLES20.glCreateProgram();
GLES20.glAttachShader(mProgram, vertexShader);
GLES20.glAttachShader(mProgram, fragmentShader);
GLES20.glLinkProgram(mProgram);
}
// Draw the shape
public void draw(float[] mvpMatrix) {
GLES20.glUseProgram(mProgram);
mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
GLES20.glEnableVertexAttribArray(mPositionHandle);
GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);
MVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
// get handle to fragment shader's vColor member
mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");
// Set color for drawing the triangle
// GLES20.glUniform4fv(mColorHandle, 1, color, 0);
GLES20.glEnableVertexAttribArray(mColorHandle);
GLES20.glVertexAttribPointer(mColorHandle, COORDS_PER_COLOR, GLES20.GL_FLOAT, false,
colorStride, colorsBuffer);
GLES20.glUniformMatrix4fv(MVPMatrixHandle, 1, false, mvpMatrix, 0);
GLES20.glDrawElements(GLES20.GL_TRIANGLES, 36, GLES20.GL_UNSIGNED_SHORT, drawListBuffer);
GLES20.glDisableVertexAttribArray(mPositionHandle);
}
}
答案 0 :(得分：0)
您没有对着色器程序中的颜色数据执行任何操作，因此您上传的数据并没有对其执行任何操作。
您需要将新顶点属性的处理代码添加到着色器;像这样的东西：
private final String vertexShaderCode =
"uniform mat4 uMVPMatrix;" +
"attribute vec4 vPosition;" +
"attribute mediump vec4 vColor;" +
"varying mediump vec4 vaColor;" +
"void main() {" +
" vaColor = vColor;" +
" gl_Position = uMVPMatrix * vPosition;" +
"}";
private final String fragmentShaderCode =
"precision mediump float;" +
"varying mediump vec4 vaColor;" +
"void main() {" +
" gl_FragColor = vaColor;" +
"}";