ps1bsp/draw.h

#ifndef __DRAW_H__
#define __DRAW_H__

#include "common.h"
#include "display.h"
#include <inline_c.h>

static INLINE void draw_triangle_fan(SVECTOR *verts, u_char numVerts)
{
    int p;

    if (!mem_checkprim(sizeof(POLY_G3), numVerts - 2))
        return;

    // Draw the face as a triangle fan
    u_char maxVert = numVerts - 1;
    for (int vertIdx = 1; vertIdx < maxVert; ++vertIdx)
    {
        const SVECTOR *v0 = &verts[0];
        const SVECTOR *v1 = &verts[vertIdx];
        const SVECTOR *v2 = &verts[vertIdx + 1];

        // Naively draw the triangle with GTE, nothing special or optimized about this
        gte_ldv3(v0, v1, v2);
        gte_rtpt();     // Rotation, translation, perspective projection

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

        // Draw a flat-shaded untextured colored triangle
        POLY_G3 *poly = (POLY_G3*)mem_prim(sizeof(POLY_G3));
        setPolyG3(poly);
        gte_stsxy3_g3(poly);

        poly->r0 = poly->g0 = poly->b0 = (uint8_t)v0->pad;
        poly->r1 = poly->g1 = poly->b1 = (uint8_t)v1->pad;
        poly->r2 = poly->g2 = poly->b2 = (uint8_t)v2->pad;

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

static INLINE void draw_triangle_strip(SVECTOR *verts, u_char numVerts)
{
    int p;

    u_char numTris = numVerts - 2;
    if (!mem_checkprim(sizeof(POLY_G3), numTris))
        return;

    // Draw the face as a triangle strip
    const SVECTOR *v0, *v1, *v2;
    const SVECTOR *head = verts;
    const SVECTOR *tail = verts + numVerts;
    u_char reverse = 0;

    v2 = head++;    // Initialize first vertex to index 0 and set head to index 1

    for (u_char triIdx = 0; triIdx < numTris; ++triIdx)
    {
        if (reverse ^= 1)
        {
            v0 = v2;
            v1 = head;
            v2 = --tail;
        }
        else
        {
            v0 = v1;
            v1 = ++head;
            v2 = tail;
        }

        // Naively draw the triangle with GTE, nothing special or optimized about this
        gte_ldv3(v0, v1, v2);
        gte_rtpt();     // Rotation, translation, perspective projection

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

        // Draw a flat-shaded untextured colored triangle
        POLY_G3 *poly = (POLY_G3*)mem_prim(sizeof(POLY_G3));
        setPolyG3(poly);
        gte_stsxy3_g3(poly);

        poly->r0 = poly->g0 = poly->b0 = (uint8_t)v0->pad;
        poly->r1 = poly->g1 = poly->b1 = (uint8_t)v1->pad;
        poly->r2 = poly->g2 = poly->b2 = (uint8_t)v2->pad;

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

static INLINE void draw_quad_strip(SVECTOR *verts, u_char numVerts)
{
    int p;

    u_char numQuads = (numVerts - 1) / 2;
    if (!mem_checkprim(sizeof(POLY_G4), numQuads))
        return;

    // Draw the face as a quad strip
    const SVECTOR *v0, *v1, *v2, *v3;
    const SVECTOR *head = verts;
    const SVECTOR *tail = verts + numVerts;

    // Initialize the first two vertices
    v2 = --tail;
    v3 = head++;

    // Normally a quad strip would have (N-2)/2 quads, but we might end up with a sole triangle at the end which will be drawn as a collapsed quad
    for (u_char quadIdx = 0; quadIdx < numQuads; ++quadIdx)
    {
        v0 = v2;
        v1 = v3;
        v2 = --tail;
        v3 = head++;

        // Naively draw the quad with GTE, nothing special or optimized about this
        gte_ldv3(v0, v1, v2);
        gte_rtpt();     // Rotation, translation, perspective projection

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

        // Draw a flat-shaded untextured colored quad
        POLY_G4 *poly = (POLY_G4*)mem_prim(sizeof(POLY_G4));
        setPolyG4(poly);
        gte_stsxy0(&poly->x0);
        gte_stsxy1(&poly->x1);
        gte_stsxy2(&poly->x2);

        // Transform the fourth vertex to complete the quad
        gte_ldv0(v3);
        gte_rtps();
        gte_stsxy(&poly->x3);

        poly->r0 = poly->g0 = poly->b0 = (uint8_t)v0->pad;
        poly->r1 = poly->g1 = poly->b1 = (uint8_t)v1->pad;
        poly->r2 = poly->g2 = poly->b2 = (uint8_t)v2->pad;
        poly->r3 = poly->g3 = poly->b3 = (uint8_t)v3->pad;

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

static INLINE void draw_quad_strip_tex(STVECTOR *verts, u_char numVerts, u_short tpage)
{
    int p;

    // Normally a quad strip would have (N-2)/2 quads, but we might end up with a sole triangle at the end which will be drawn as a collapsed quad
    u_char numQuads = (numVerts - 1) / 2;
    if (!mem_checkprim(sizeof(POLY_GT4), numQuads))
        return;

    // Draw the face as a quad strip
    const STVECTOR *v0, *v1, *v2, *v3;
    const STVECTOR *head = verts;
    const STVECTOR *tail = verts + numVerts;

    // Initialize the first two vertices
    v2 = --tail;
    v3 = head++;

    for (u_char quadIdx = 0; quadIdx < numQuads; ++quadIdx)
    {
        v0 = v2;
        v1 = v3;
        v2 = --tail;
        v3 = head++;

        // Naively draw the quad with GTE, nothing special or optimized about this
        gte_ldv3(v0, v1, v2);
        gte_rtpt();     // Rotation, translation, perspective projection

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

        // Draw a flat-shaded untextured colored quad
        POLY_GT4 *poly = (POLY_GT4*)mem_prim(sizeof(POLY_GT4));
        setPolyGT4(poly);
        gte_stsxy0(&poly->x0);
        gte_stsxy1(&poly->x1);
        gte_stsxy2(&poly->x2);

        // Transform the fourth vertex to complete the quad
        gte_ldv0(v3);
        gte_rtps();
        gte_stsxy(&poly->x3);

        // Texture UVs
        setUV4(poly, v0->u, v0->v, v1->u, v1->v, v2->u, v2->v, v3->u, v3->v);
        poly->clut = quake_clut;
        poly->tpage = tpage;

        // Vertex color lighting
        poly->r0 = poly->g0 = poly->b0 = (uint8_t)v0->pad;
        poly->r1 = poly->g1 = poly->b1 = (uint8_t)v1->pad;
        poly->r2 = poly->g2 = poly->b2 = (uint8_t)v2->pad;
        poly->r3 = poly->g3 = poly->b3 = (uint8_t)v3->pad;

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

#endif  // __DRAW_H__