Diagonal Textures

[ragnarok2040]

Code: Select all

|====================================================|
| 1        1 = 0.5,0.0 2 = 1.0,0.5                   |
|3 2                               up-right          |
| 4        3 = 0.0,0.5 4 = 0.5,1.0                   |
|====================================================|

I'm trying to figure out how to draw a texture diagonally, I didn't feel like using 30 or so ship images, so I'm doing it by changing the u,v values for each vertex of the polygon I'm mapping it on.

1 = (u1,v1) 2= (u2,v2) 3= (u3,v3) 4= (u4,v4)

This displays it diagonally, but messed up on the sides (the corner between 3,1, and the corner between 2,4). I'm pretty sure I don't have the correct u,v coords for each vertex. I have up, down, left, right working, tho.

Is there a formula or anything to figure this out?

[Tangent]

Have you considered trying to rotate the polygon?

[BlackAura]

Rotate the ship polygon itself - it's much easier. I'll see if I can find some code to do it. How are you rendering stuff - KGL or PVR?

[ragnarok2040]

I'm using the pvr to do it, DCGrendel gave me some code to do rotation, but I don't really understand it.

Code: Select all

typedef struct ship_s {
	int type;
	float x,y,z;
	float rot;
} ship_t;
ship_t player_ship;
...
	player_ship.rot = 0;

	u1=sinf(player_ship.rot-45);
	u2=sinf(player_ship.rot+135);
	v1=cosf(player_ship.rot-45);
	v2=cosf(player_ship.rot+135);

	x1=player_ship.x+u1;
	x2=player_ship.x+u2;
	y1=player_ship.x+v1;
	y2=player_ship.x+v2;

	u1+=0.5f;
	u2+=0.5f;
	v1+=0.5f;
	v2+=0.5f;

	render_object(texture, tx, ty, x1, y1, player_ship.z, x2, y2, u1, v1, u2, v2);

uhm, ok, to move the ship, you do mx+=sin(player_ship.rot); my+=cos(player_ship.rot);
to rotate it you + or - player_ship.rot

I pretty much have it figured out, but I don't really know how to implement the u1,v1 and u2,v2 in the draw function.

This is how I have it setup right now:

Code: Select all

void draw_ship(int x2, int y2, int z2, float u1, float v1, float u2, float v2, float u3, float v3, float u4, float v4, char *ship_tex)
{
    pvr_poly_cxt_t cxt;
    pvr_poly_hdr_t hdr;
    pvr_vertex_t vert2;

    pvr_poly_cxt_txr(&cxt, PVR_LIST_TR_POLY, PVR_TXRFMT_ARGB4444, 64, 64, ship_tex, PVR_FILTER_BILINEAR);
    pvr_poly_compile(&hdr, &cxt);
    pvr_prim(&hdr, sizeof(hdr));


    vert2.argb = PVR_PACK_COLOR(1,1,1,1);    
    vert2.oargb = 0;
    vert2.flags = PVR_CMD_VERTEX;
    
    vert2.x = 1 + x2;
    vert2.y = 1 + y2;
    vert2.z = z2;
    vert2.u = u1;
    vert2.v = v1;
    pvr_prim(&vert2, sizeof(vert2));
    
    vert2.x = 64 + x2;
    vert2.y = 1 + y2;
    vert2.z = z2;
    vert2.u = u2;
    vert2.v = v2;
    pvr_prim(&vert2, sizeof(vert2));
    
    vert2.x = 1 + x2;
    vert2.y = 64 + y2;
    vert2.z = z2;
    vert2.u = u3;
    vert2.v = v3;
    pvr_prim(&vert2, sizeof(vert2));
    
    vert2.x = 64 + x2;
    vert2.y = 64 + y2;
    vert2.z = z2;
    vert2.u = u4;
    vert2.v = v4;
    vert2.flags = PVR_CMD_VERTEX_EOL;
    pvr_prim(&vert2, sizeof(vert2));
}

With u1,v1 u2,v2 and etc. for each vertex point, it was easier to figure out what they should be, heh.

*EDIT*
Nevermind, found out that it was easier to rotate the poly than the textures , just starting out graphics programming.

/me says thanks to Sayten