java - 在opengl es 2.0中绘制纹理

Question

我在 android 上的 opengl es 2 中绘制纹理时遇到了大约 3 天的问题，最终决定我应该提供帮助，因为我的所有研究都陷入了死胡同。问题是纹理被绘制为黑色矩形而不是实际图像。

public class Sprite 
{
    private static final Shader spriteShader = ShaderManager.getInstance().getShader(1);
    private static final short[] drawOrder = { 0, 1, 2, 0, 2, 3 };
    private static ShortBuffer drawListBuffer;

    static 
    {
        ByteBuffer bb = ByteBuffer.allocateDirect(drawOrder.length * 2);
        bb.order(ByteOrder.nativeOrder());

        drawListBuffer = bb.asShortBuffer();
        drawListBuffer.put(drawOrder);
        drawListBuffer.position(0);     
    }

    private Context m_context;
    private int m_textureId = 0;
    private FloatBuffer m_vertexBuffer;
    private float[] m_coords = 
        {
            -0.5f,  0.5f, 0.0f, // Position 0
             0.0f,  0.0f, // TexCoord 0
            -0.5f, -0.5f, 0.0f, // Position 1
             0.0f,  1.0f, // TexCoord 1
             0.5f, -0.5f, 0.0f, // Position 2
             1.0f,  1.0f, // TexCoord 2
             0.5f,  0.5f, 0.0f, // Position 3
             1.0f,  0.0f // TexCoord 3
        };


    public Sprite(Context context)
    {
        m_context = context;

        ByteBuffer bb = ByteBuffer.allocateDirect(m_coords.length * 4);
        bb.order(ByteOrder.nativeOrder());

        m_vertexBuffer = bb.asFloatBuffer();
        m_vertexBuffer.put(m_coords);
        m_vertexBuffer.position(0);
    }

    public void initialize(String file)
    {
        InputStream inputStream = null;

        try 
        {
            inputStream = m_context.getAssets().open(file);
            m_textureId = loadTexture(inputStream);
        } 
        catch (IOException e) 
        {}
        finally
        {
            Util.closeStream(inputStream);
        }
    }

    public void draw()
    {
        spriteShader.use();

        int position = spriteShader.getAttribLocation("vPosition");
        int textureCoords = spriteShader.getAttribLocation("aTexCoords");
        int texture = spriteShader.getUniformLocation("uTexture");

        m_vertexBuffer.position(0);
        GLES20.glVertexAttribPointer(position, 3, GLES20.GL_FLOAT, false, 20, m_vertexBuffer);
        Util.checkGlError("vertex pointer poistion");
        m_vertexBuffer.position(3);
        GLES20.glVertexAttribPointer(textureCoords, 2, GLES20.GL_FLOAT, false, 20, m_vertexBuffer);
        Util.checkGlError("vertex pointer textureCoords");
        GLES20.glEnableVertexAttribArray(position);
        GLES20.glEnableVertexAttribArray(textureCoords);

        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        Util.checkGlError("active trexture");
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, m_textureId);
        Util.checkGlError("bind texture");

        GLES20.glUniform1i(texture, 0);
        Util.checkGlError("uniform1i");
        GLES20.glDrawElements(GLES20.GL_TRIANGLES, drawOrder.length, GLES20.GL_UNSIGNED_SHORT, drawListBuffer);
        Util.checkGlError("drawelements");

    }

    private int loadTexture(InputStream inputStream)
    {
        int[] texture = new int[1];
        GLES20.glGenTextures(1, texture, 0);

        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture[0]); 

        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_NEAREST);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);

        Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
        GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
        bitmap.recycle();

        return texture[0];
    }
}

顶点着色器

attribute vec2 aTexCoords;
attribute vec4 vPosition;

varying vec2 vTexCoords;

void main()
{
vTexCoords = aTexCoords;
gl_Position = vPosition;
}

fragment 着色器

precision mediump float;

uniform sampler2D uTexture;
varying vec2 vTexCoords;

void main()
{
gl_FragColor = texture2D(uTexture, vTexCoords);
}

Answer 1

您可以尝试为顶点坐标和纹理坐标使用单独的数组。

private float[] texCoords = {0,0,
                             0,1,
                             1,1,
                             1,0};

并为纹理坐标创建一个单独的 float 缓冲区。您还可以在 glVertexAtrribPointer 调用中使用步幅值 0，这意味着数组被认为是紧密包装的。