tsoding.olive.c/demos/dots3d.c

#include "vc.c"

float sqrtf(float x);
float atan2f(float y, float x);
float sinf(float x);
float cosf(float x);

#define PI 3.14159265359

#define WIDTH 960
#define HEIGHT 720
#define BACKGROUND_COLOR 0xFF181818
#define GRID_COUNT 10
#define GRID_PAD 0.5/GRID_COUNT
#define GRID_SIZE ((GRID_COUNT - 1)*GRID_PAD)
#define CIRCLE_RADIUS 5
#define Z_START 0.25
#define ABOBA_PADDING 50

static uint32_t pixels[WIDTH*HEIGHT];
static float angle = 0;

Olivec_Canvas vc_render(float dt)
{
    angle += 0.25*PI*dt;

    Olivec_Canvas oc = olivec_canvas(pixels, WIDTH, HEIGHT, WIDTH);

    olivec_fill(oc, BACKGROUND_COLOR);
    for (int ix = 0; ix < GRID_COUNT; ++ix) {
        for (int iy = 0; iy < GRID_COUNT; ++iy) {
            for (int iz = 0; iz < GRID_COUNT; ++iz) {
                float x = ix*GRID_PAD - GRID_SIZE/2;
                float y = iy*GRID_PAD - GRID_SIZE/2;
                float z = Z_START + iz*GRID_PAD;

                float cx = 0.0;
                float cz = Z_START + GRID_SIZE/2;

                float dx = x - cx;
                float dz = z - cz;

                float a = atan2f(dz, dx);
                float m = sqrtf(dx*dx + dz*dz);

                dx = cosf(a + angle)*m;
                dz = sinf(a + angle)*m;

                x = dx + cx;
                z = dz + cz;

                x /= z;
                y /= z;

                uint32_t r = ix*255/GRID_COUNT;
                uint32_t g = iy*255/GRID_COUNT;
                uint32_t b = iz*255/GRID_COUNT;
                uint32_t color = 0xFF000000 | (r<<(0*8)) | (g<<(1*8)) | (b<<(2*8));
                olivec_circle(oc, (x + 1)/2*WIDTH, (y + 1)/2*HEIGHT, CIRCLE_RADIUS, color);
            }
        }
    }

    size_t size = 8;
    olivec_text(oc, "aboba", ABOBA_PADDING, HEIGHT - ABOBA_PADDING - olivec_default_font.height*size, olivec_default_font, size, 0xFFFFFFFF);

    return oc;
}