纹理创建

接上一节，纹理创建使用的函数是gs_texture_create。

//必须的2的整数倍，并且大于1
static inline bool is_pow2(uint32_t size)
{
    return size >= 2 && (size & (size - 1)) == 0;
}

gs_texture_t *gs_texture_create(uint32_t width, uint32_t height,
                enum gs_color_format color_format,
                uint32_t levels, const uint8_t **data,
                uint32_t flags)
{
    graphics_t *graphics = thread_graphics;
    bool pow2tex = is_pow2(width) && is_pow2(height);
    bool uses_mipmaps = (flags & GS_BUILD_MIPMAPS || levels != 1);

    if (!gs_valid("gs_texture_create"))
        return NULL;

    if (uses_mipmaps && !pow2tex) 
    {
        uses_mipmaps = false;
        flags &= ~GS_BUILD_MIPMAPS;
        levels = 1;
    }

    if (uses_mipmaps && flags & GS_RENDER_TARGET)
    {
        blog(LOG_WARNING, "Cannot use mipmaps with render targets.  "
                  "Disabling mipmaps for this texture.");
        flags &= ~GS_BUILD_MIPMAPS;
        levels = 1;
    }

    return graphics->exports.device_texture_create(graphics->device, width, height,
    color_format, levels,
    data, flags);
}

device_texture_create对应的其实是D3D11的device_texture_create函数。该函数就是创建一个2D纹理。

gs_texture_t *device_texture_create(gs_device_t *device, uint32_t width,
                    uint32_t height,
                    enum gs_color_format color_format,
                    uint32_t levels, const uint8_t **data,
                    uint32_t flags)
{
    gs_texture *texture = NULL;
    try {
        texture = new gs_texture_2d(device, width, height, color_format,
                        levels, data, flags, GS_TEXTURE_2D,
                        false);
    } catch (const HRError &error) {
        blog(LOG_ERROR, "device_texture_create (D3D11): %s (%08lX)",
             error.str, error.hr);
        LogD3D11ErrorDetails(error, device);
    } catch (const char *error) {
        blog(LOG_ERROR, "device_texture_create (D3D11): %s", error);
    }

    return texture;
}

2d纹理，使用结构体gs_texture_2d。其基类为gs_texture。更多细节可见：https://www.vaczh.com/article/detail-93.html