Sega Saturn Development > General Jo Engine Help

TGA 8-bit in background

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FranMatsusaka:
Hi,

I'm doing a Resident Evil like game, with 3d characters moving on a prerendered backgound, and I'm finding memory out problems.
I've seen that 8bit sprite is implemented and working, but I couldn't find a way to load TGA 8bit background. I've seen that there's a jo_img_8bits object type, and a jo_set_background_8bits_sprite, but I couldn't find a 8bit version of jo_tga_loader function. How can I load a 8bit TGA into a jo_img_8bits object?

Thanks in advance.

ponut64:
Check the "demo - vdp2 plane".

While not exactly what you want, it does demonstrate the process of loading an indexed color targa file to a VDP2 background layer.
You could copy this structure entirely, and simply not rotate the background layer.

FranMatsusaka:

--- Quote from: ponut64 on January 21, 2022, 11:07:40 pm ---Check the "demo - vdp2 plane".

While not exactly what you want, it does demonstrate the process of loading an indexed color targa file to a VDP2 background layer.
You could copy this structure entirely, and simply not rotate the background layer.

--- End quote ---

Thank you very much! I fell a little silly because I couldn't find that jo_set_background_8bits_sprite by myself... Anyway, I have removed old code and substituted by all 8bit versions. I have not worked properly on the palette yet, but besides that it looks like there's some kind of corruption.

Here's the old code commented and the new:

--- Code: ---
        //jo_img  bg;
        //bg.data = NULL;
        //jo_tga_loader(&bg, "BGO", image_to_load, JO_COLOR_Transparent);
        //if (bg.data != NULL) {
            //jo_set_background_sprite(&bg, 0, 0);
            //jo_free_img(&bg);
        //}
       
        jo_img_8bits bg;
        bg.data = NULL;
        jo_tga_8bits_loader(&bg, "BG8", image_to_load, JO_COLOR_Transparent);
       
        if (bg.data != NULL) {
            jo_set_background_8bits_sprite(&bg, 0, false);
            jo_free_img(&bg);
        }

--- End code ---

And here's te result... it looks like the tiles are displayed with some extra offset. Also, it looks like the tiles are 90º rotated


This is the original TGA in case anybody wants to check
https://drive.google.com/file/d/1qvcGEQqIViJUClh37X4_T9KCrY5eNPUk/view?usp=sharing

FranMatsusaka:
Palette fixed:

FranMatsusaka:
I was able to "fix" it by making few changes in the library. It seems it was storing cells/tiles and map indexes horizontally. I don't know if this was done like this because of mode7 plane . If anybody want's to load 8bit tgas in the background, you will need to make small hacks/changes in __jo_create_map and jo_img_to_vdp2_cells in vdp2.c

Though, this could potentially break something else...


--- Code: ---
void                            jo_img_to_vdp2_cells(const jo_img_8bits * const img, const bool vertical_flip, unsigned char *cell)
{
    register int                x;
    register int                y;
    register int                cell_x;
    register int                cell_y;
    register int                line_y;
    register int                i;


#ifdef JO_DEBUG
        if (img == JO_NULL)
        {
            jo_core_error("img is null");
            return ;
        }
        if (JO_MOD_POW2(img->width, 8) != 0)
        {
            jo_core_error("Image width must be multiple of 8");
            return ;
        }
        if (JO_MOD_POW2(img->height, 8) != 0)
        {
            jo_core_error("Image height must be multiple of 8");
            return ;
        }
#endif

    for (JO_ZERO(y), JO_ZERO(line_y); y < img->height; y += CELL_HEIGHT, line_y += JO_MULT_BY_8(img->width))
    {
        for (JO_ZERO(x); x < img->width; x += CELL_WIDTH)
        {
            cell_x = x;
            cell_y = line_y;
            for (JO_ZERO(i); i < CELL_SIZE; ++i, ++cell, ++cell_x)
            {
                if (i != 0 && JO_MOD_POW2(i, CELL_WIDTH) == 0)
                {
                    cell_x -= CELL_WIDTH;
                    cell_y += img->width;
                }
                /**/
                if (vertical_flip)
                    *cell = img->data[(img->width - cell_x - 1) + cell_y];
                else
                 /**/
                    *cell = img->data[cell_x + cell_y];
            }
        }
    }
}

static void                     __jo_create_map(const jo_img_8bits * const img, unsigned short *map, const unsigned short palette_id, const int map_offset)
{
    register int                x;
    register int                y;
    register int                x2;
    register int                y2;
    register int                i;
    unsigned short              paloff;

    paloff = JO_MULT_BY_4096(palette_id);
    y = JO_DIV_BY_8(img->height);
    x = JO_DIV_BY_8(img->width);
    JO_ZERO(y2);
    JO_ZERO(x2);
    for (JO_ZERO(i); i < MAP_LENGTH; ++i)
    {
/*
        if (i != 0 && JO_MOD_POW2(i, CELL_COUNT_PER_ROW) == 0)
            ++y2;
        if (y2 >= y)
            JO_ZERO(y2);
        *map = (JO_MULT_BY_2(x2 + y2 * y) | paloff) + map_offset;
            ++map;
        ++x2;
        if (x2 >= x)
            JO_ZERO(y2);

/**/
        if (i != 0 && JO_MOD_POW2(i, CELL_COUNT_PER_ROW) == 0) {
            JO_ZERO(x2);
            ++y2;
            /*
            if (y2 >= y) {
                JO_ZERO(y2);
            }*/
        }
        *map = (JO_MULT_BY_2(x2 + y2 * x) | paloff) + map_offset;
       
        ++map;
        ++x2;
/**/       
    }
}

--- End code ---

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