#include "common.h"
#include "world.h"
#include "display.h"

#include <inline_c.h>

static CVECTOR colors[] = 
{
    { 255, 0, 0 },
    { 0, 255, 0 },
    { 0, 0, 255 },
    { 255, 255, 0 },
    { 255, 0, 255 },
    { 0, 255, 255 },
    { 128, 255, 0 },
    { 255, 128, 0 },
    { 128, 0, 255 },
    { 255, 0, 128 },
    { 0, 128, 255 },
    { 0, 255, 128 },
};
static const int numColors = sizeof(colors) / sizeof(CVECTOR);

void world_load(const u_long *data, world_t *world)
{
    const char *bytes = (const char*)data;

    world->header = (ps1bsp_header_t*)bytes;
    bytes += sizeof(ps1bsp_header_t);

    world->vertices = (ps1bsp_vertex_t*)bytes;
    bytes += sizeof(ps1bsp_vertex_t) * world->header->numVertices;

    world->faceVertIndices = (unsigned short*)bytes;
    bytes += sizeof(unsigned short) * world->header->numFaceVertIndices;

    world->faces = (ps1bsp_face_t*)bytes;
    bytes += sizeof(ps1bsp_face_t) * world->header->numFaces;
}

void world_draw(const world_t *world)
{
    int p;

    // The world doesn't move, so we just set the camera view-projection matrix
    gte_SetRotMatrix(&vp_matrix);
	gte_SetTransMatrix(&vp_matrix);

    for (int faceIdx = 0; faceIdx < world->header->numFaces; ++faceIdx)
    {
        const ps1bsp_face_t *face = &world->faces[faceIdx];
        const CVECTOR *col = &colors[faceIdx % numColors];

        char *scratch = scratchpad;
        SVECTOR *vecs = (SVECTOR*)mem_scratch(&scratch, sizeof(SVECTOR) * face->numVertices);

        // Copy this face's vertices into scratch RAM for fast reuse
        unsigned short *faceVertIndex = &world->faceVertIndices[face->firstVertexIndex];
        for (int vertIdx = 0; vertIdx < face->numVertices; ++vertIdx, ++faceVertIndex)
        {
            vecs[vertIdx] = *((SVECTOR*)&world->vertices[*faceVertIndex]);
        }

        // Draw the face as a triangle fan
        for (int vertIdx = 1; vertIdx < face->numVertices - 1; ++vertIdx)
        {
            // Naively draw the triangle with GTE, nothing special or optimized about this
            gte_ldv3(&vecs[0], &vecs[vertIdx], &vecs[vertIdx + 1]);
            gte_rtpt();     // Rotation, translation, perspective projection

            // Normal clipping for backface culling
            gte_nclip();
            gte_stopz(&p);
            if (p < 0)
                continue;

            // Average Z for depth sorting and culling
            gte_avsz3();
            gte_stotz(&p);
            unsigned short depth = p >> 2;
            if (depth <= 0 || depth >= OTLEN)
                continue;

            // Draw a flat-shaded untextured colored triangle
            POLY_F3 *poly = (POLY_F3*)mem_prim(sizeof(POLY_F3));
            if (poly == NULL)
                break;

            setPolyF3(poly);

            gte_stsxy3_f3(poly);

            poly->r0 = col->r;
            poly->g0 = col->g;
            poly->b0 = col->b;

            addPrim(curOT + depth, poly);
        }
    }
}