main.c

unsigned char globalsEndHere;

#include "nstdlib.h"
#include "olduino.h"

#define SIMULATOR

float abs(float x);
float sqrt(float x);
void raySphereIntersection(float posX, float posY, float posZ, float origX, float origY, float origZ, float dirX, float dirY, float dirZ, float radius, float* t0, float* t1);
//const char brightnessSymbols[] = {176, 177, 178, 219};
const char brightnessSymbols[] = {'.', '=', 'x', '#'};

void main() {
    int i,j;
    char pRes;
    float rayX,rayY,rayZ,length,t0,t1,origX,origY,origZ,posX,posY,posZ;
    memcpy((void *)0xe000, (void *)0x6000, 0x1fff);
    t0 = t1 = 1.0;
    printf("Raytracing test 1802\r\n");

    printf("Pre-run test: Does abs function work?");
    rayX = 5.0;
    rayY = -7.0;
    if(abs(rayX) == 5.0 && abs(rayY) == 7.0) printf("\tYes\r\n");
    else {
        printf("\tNo\r\n");
        goto abort;
    }

    printf("Pre-run test: Does square-root function work?");
    rayX = 2.0;
    rayX = sqrt(rayX);
    if((int)(rayX * 1000.0) == 1414) printf("\tYes\r\n");
    else {
        printf("\tNo\r\n");
        goto abort;
    }

    printf("Pre-run test: Does ray-sphere-intersection function work?");
    raySphereIntersection(0.02, 0.02, 3.0, 0.01, 0.01, 0.01, -0.231, 0.033, 0.972, 1.0, &t0, &t1);
    if((long)(t0 * 1000.0) != 2200 || (long)(t1 * 1000.0) != 3607) {
        printf("\tNo\r\n");
        goto abort;
    }
    raySphereIntersection(0.02, 0.02, 3.0, 0.01, 0.01, 0.01, -0.231, -0.601, 0.765, 1.0, &t0, &t1);
    if(t0 == 10000.0 && t1 == 10000.0) printf("\tYes\r\n");
    else {
        printf("\tNo\r\n");
        goto abort;
    }

    printf("\r\nBEGIN RENDER\r\n");
    for(i = 0; i < 150; i++) putc('-');
    putc('\r');
    putc('\n');
    for(i = 0; i < 64; i++) {
#ifndef SIMULATOR
        if(i % 2 == 0) asm("    seq\n");
        else asm("  req\n");
#endif
        for(j = 0; j < 128; j++) {
            pRes = ' ';
            rayX = (float)i / 63.0 - 0.5;
            rayX *= 2.0;
            rayY = -(float)j / 127.0 - 0.5;
            rayY *= 2.0;
            rayZ = 1.0;

            origX = origY = origZ = 0.01;

            length = sqrt(rayX * rayX + rayY * rayY + rayZ * rayZ);
            rayX /= length;
            rayY /= length;
            rayZ /= length;

            raySphereIntersection(0.02, 0.02, 2.0, origX, origY, origZ, rayX, rayY, rayZ, 1.0, &t0, &t1);
            if(t0 < 9000) {
                posX = (origX + t0 * rayX) - 0.2;
                posY = (origY + t0 * rayY) - 0.2;
                posZ = (origZ + t0 * rayZ) - 3.0;
                length = sqrt(posX * posX + posY * posY + posZ * posZ);
                posX /= length;
                posY /= length;
                posZ /= length;

                length = -posX * posX + (10000.0 - posY) * posY + (-3200.0 - posZ) * posZ;
                length /= 1500.0;
                if(length >= 1.0) length = 0.995;
                if(length < 0) length = 0;
                pRes = brightnessSymbols[(char)(length * 4.0)];
            }

            putc(pRes);
        }
        putc('\r');
        putc('\n');
    }
    for(i = 0; i < 150; i++) putc('-');
    putc('\r');
    putc('\n');

    loop_forever:
    while(1){
#ifndef SIMULATOR
        asm("   seq\n");
        for(i = 0; i < 16384; i++) {}
        asm("   req\n");
        for(i = 0; i < 16384; i++) {}
#endif
        asm("   nop\n");
    }
    abort:
        printf("Abort!\r\n");
        goto loop_forever;
}

float abs(float x) {
    return x < 0 ? 0.0 - x : x;
}

float sqrt(float x) {
    float x2,y = 0;
    long i;

    if(x == 0.0) return 0.0;
    x2 = x * 0.5f;
    i = *(long *)&x;
    i = 0x5f3759dfL - (i >> 1);
    y = *(float *)&i;
    y *= 1.5f - (x2 * y * y);
    y *= 1.5f - (x2 * y * y);
    return 1.0 / y;
}

void raySphereIntersection(float posX, float posY, float posZ, float origX, float origY, float origZ, float dirX, float dirY, float dirZ, float radius, float* t0, float* t1) {
    float Lx,Ly,Lz,tca,L_2,d,thc;

    if(dirX == 0) dirX = 1e-3;
    if(dirY == 0) dirY = 1e-3;
    if(dirZ == 0) dirZ = 1e-3;

    *t0 = 10000.0;
    *t1 = 10000.0;

    Lx = posX - origX;
    Ly = posY - origY;
    Lz = posZ - origZ;

    tca = dirX * Lx;
    tca += dirY * Ly;
    tca += dirZ * Lz;
    L_2 = Lx * Lx + Ly * Ly + Lz * Lz;
    if(tca <= 0 && sqrt(L_2) >= radius) return;

    d = L_2 - tca * tca;
    if(sqrt(d) >= radius) return;

    thc = radius * radius - d;
    thc = sqrt(thc);

    *t0 = tca - thc;
    *t1 = tca + thc;
}

unsigned char globalsStartHere;

#include "nstdlib.c"
#include "olduino.c"