Question

我试图找出如何创建顶点缓冲区以在屏幕上绘制彩色方块网格。大小为108 x 192（屏幕分辨率）。我试着查看this code获取GLES32并重新制作Square类以生成多色网格，但没有成功。

有人能给我一个例子，我可以学习如何用GLES32.glDrawArrays创建一个位置+颜色顶点来创建网格吗？

最终目标是创建一个使用VSync（无混合）的多色方格网格，最重要的是，我可以使用特定的rgb值在每次扫描时更新，所以它看起来像这样：

Imgur

我非常感谢任何帮助。

这是我到目前为止基于this thread：

import android.opengl.GLES32;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;

/**
 * A two-dimensional square for use as a drawn object in OpenGL ES 2.0.
 */
public class Square {

    private final String vertexShaderCode =
            // This matrix member variable provides a hook to manipulate
            // the coordinates of the objects that use this vertex shader
            "uniform mat4 uMVPMatrix;" +
            "attribute vec4 vPosition;" +
            "void main() {" +
            // The matrix must be included as a modifier of gl_Position.
            // Note that the uMVPMatrix factor *must be first* in order
            // for the matrix multiplication product to be correct.
            "  gl_Position = uMVPMatrix * vPosition;" +
            "}";

    private final String fragmentShaderCode =
            "precision mediump float;" +
            "uniform vec4 vColor;" +
            "void main() {" +
            "  gl_FragColor = vColor;" +
            "}";

    private final FloatBuffer vertexBuffer;
    private final ShortBuffer drawListBuffer;
    private final int mProgram;
    private int mPositionHandle;
    private int mColorHandle;
    private int mMVPMatrixHandle;


    private static int GRID_ROWS = 108;
    private static int GRID_COLS = 192;

    // number of coordinates per vertex in this array
    static final int COORDS_PER_VERTEX = 3;
    private float[] mVertices;
    private short[] mIndices;

    private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex

    float color[] = { 0.2f, 0.709803922f, 0.898039216f, 1.0f };


    void makePlane(int rows, int columns) {

        mVertices = new float[rows*columns*COORDS_PER_VERTEX*2];
        mIndices = new short[rows*columns*COORDS_PER_VERTEX*2];

        // Set up mVertices
        for (int r = 0; r < rows; ++r) {
            for (int c = 0; c < columns; ++c) {
                int index = r*columns + c;
                mVertices[3*index + 0] = (float) c;
                mVertices[3*index + 1] = (float) r;
                mVertices[3*index + 2] = 0.0f;
            }
        }

        // Set up mIndices
        int i = 0;
        for (int r = 0; r < rows - 1; ++r) {
            mIndices[i++] = (short) (r * columns);
            for (int c = 0; c < columns; ++c) {
                mIndices[i++] = (short) (r * columns + c);
                mIndices[i++] = (short) ((r + 1) * columns + c);
            }
            mIndices[i++] = (short) ((r + 1) * columns + (columns - 1));
        }
    }

    /**
     * Sets up the drawing object data for use in an OpenGL ES context.
     */
    public Square() {

        // Prepare vertices and indices
        makePlane(GRID_ROWS, GRID_COLS);

        // initialize vertex byte buffer for shape coordinates
        ByteBuffer bb = ByteBuffer.allocateDirect(
        // (# of coordinate values * 4 bytes per float)
                mVertices.length * 4);
        bb.order(ByteOrder.nativeOrder());
        vertexBuffer = bb.asFloatBuffer();
        vertexBuffer.put(mVertices);
        vertexBuffer.position(0);

        // initialize byte buffer for the draw list
        ByteBuffer dlb = ByteBuffer.allocateDirect(
                // (# of coordinate values * 2 bytes per short)
                mIndices.length * 2);
        dlb.order(ByteOrder.nativeOrder());
        drawListBuffer = dlb.asShortBuffer();
        drawListBuffer.put(mIndices);
        drawListBuffer.position(0);

        // prepare shaders and OpenGL program
        int vertexShader = MyGLRenderer.loadShader(
                GLES32.GL_VERTEX_SHADER,
                vertexShaderCode);
        int fragmentShader = MyGLRenderer.loadShader(
                GLES32.GL_FRAGMENT_SHADER,
                fragmentShaderCode);

        mProgram = GLES32.glCreateProgram();             // create empty OpenGL Program
        GLES32.glAttachShader(mProgram, vertexShader);   // add the vertex shader to program
        GLES32.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
        GLES32.glLinkProgram(mProgram);                  // create OpenGL program executables
    }

    /**
     * Encapsulates the OpenGL ES instructions for drawing this shape.
     *
     * @param mvpMatrix - The Model View Project matrix in which to draw
     * this shape.
     */
    public void draw(float[] mvpMatrix) {
        // Add program to OpenGL environment
        GLES32.glUseProgram(mProgram);

        // get handle to vertex shader's vPosition member
        mPositionHandle = GLES32.glGetAttribLocation(mProgram, "vPosition");

        // Enable a handle to the triangle mVertices
        GLES32.glEnableVertexAttribArray(mPositionHandle);

        // Prepare the triangle coordinate data
        GLES32.glVertexAttribPointer(
                mPositionHandle, COORDS_PER_VERTEX,
                GLES32.GL_FLOAT, false,
                vertexStride, vertexBuffer);

        // get handle to fragment shader's vColor member
        // mColorHandle = GLES32.glGetUniformLocation(mProgram, "vColor");

        // Set color for drawing the triangle
        GLES32.glUniform4fv(mColorHandle, 1, color, 0);

        // get handle to shape's transformation matrix
        mMVPMatrixHandle = GLES32.glGetUniformLocation(mProgram, "uMVPMatrix");
        MyGLRenderer.checkGlError("glGetUniformLocation");

        // Apply the projection and view transformation
        GLES32.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mvpMatrix, 0);
        MyGLRenderer.checkGlError("glUniformMatrix4fv");

        // Draw the square
        GLES32.glDrawElements(
                GLES32.GL_TRIANGLES,  mIndices.length,
                GLES32.GL_UNSIGNED_SHORT, drawListBuffer);

        // Disable vertex array
        GLES32.glDisableVertexAttribArray(mPositionHandle);
    }

}

不幸的是，它会产生以下错误：

 at edu.cs4730.helloopengles32.MyGLRenderer.checkGlError(MyGLRenderer.java:147)
                                                                              at edu.cs4730.helloopengles32.Square.draw(Square.java:167)
                                                                              at edu.cs4730.helloopengles32.MyGLRenderer.onDrawFrame(MyGLRenderer.java:73)
                                                                              at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1571)
                                                                              at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1270)

Android GLES 32 - 方格

0 个答案: