Opengl学习笔记之Texture 2D Array

Array Textures 范例来自 OpenGl SuperBible(page 177-182),并做了些改动。

1.vertex shader 中改了 vs_out.alien = alien_index % 2; 因为我使用了两张图片。sampler2DArray对象的texture()函数采样的纹理坐标参数的z即指定使用纹理数组内图片的索引。
(color = texture(tex_onePiece, vec3(fs_in.tc, float(fs_in.alien)));)

2.使用DevIL加载图片，il只需执行一次，放置在start()内

    ilInit();
    ilGenImages(2, images);

    ilEnable(IL_ORIGIN_SET);
    ilOriginFunc(IL_ORIGIN_LOWER_LEFT);

    LoadImageIndex("Lunamon.gif", 0);
    LoadImageIndex("images.jpg", 1);

    GenerateTextureObject();

    void LoadImageIndex(string imageName, int index)
    {
        ilBindImage(images[index]);
        ILboolean success = ilLoadImage(imageName.c_str());
        ilConvertImage(IL_RGBA, IL_UNSIGNED_BYTE);

        if (!success)
        {
            ilDeleteImages(1, images);
        }
    }

    void GenerateTextureObject()
    {
        // general sampler
        glGenSamplers(1, &samplers);

        glSamplerParameteri(samplers, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glSamplerParameteri(samplers, GL_TEXTURE_WRAP_T, GL_REPEAT);
        glSamplerParameteri(samplers, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glSamplerParameteri(samplers, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

        glBindSampler(textureUnit, samplers);

        // texture object and texture 2d array 
        glGenTextures(2, textures);
        glBindTexture(GL_TEXTURE_2D_ARRAY, textures[0]);
        //allocate memory: depth is the length of texture 2d array
        glTexStorage3D(GL_TEXTURE_2D_ARRAY, 1, GL_RGBA8, 100, 100, 100);

        ilBindImage(images[0]);
        int w = ilGetInteger(IL_IMAGE_WIDTH);
        int h = ilGetInteger(IL_IMAGE_HEIGHT);
        unsigned char * data = ilGetData();
        //init pixel datas: zoffset is 0
        glTexSubImage3D(GL_TEXTURE_2D_ARRAY, 0, 0, 0, 0, w, h, 1, GL_RGBA, GL_UNSIGNED_BYTE, data);

        ilBindImage(images[1]);
        int w1 = ilGetInteger(IL_IMAGE_WIDTH);
        int h1 = ilGetInteger(IL_IMAGE_HEIGHT);
        unsigned char * data1 = ilGetData();
        //init pixel datas: zoffset is 1
        glTexSubImage3D(GL_TEXTURE_2D_ARRAY, 0, 0, 0, 1, w1 , h1, 1, GL_RGBA, GL_UNSIGNED_BYTE, data1);

        // 2d texture 
        glBindTexture(GL_TEXTURE_2D, textures[1]);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w1, h1, 0, GL_RGBA, GL_UNSIGNED_BYTE, data1);

    }

在编译时遇到一些问题：
1.glTexStorage3D()与glTexSubImage3D()的参数设置有问题。google了一些资料。
OpenGL ES: Array Texture初体验
Array Textures
2.GL_TRIANGLE_STRIP

编译成功运行结果：