tsoding.olive.c/demos/triangleTex.c

#include "vc.c"
#include "assets/tsodinPog.c"

#define WIDTH 960
#define HEIGHT 720
#define BACKGROUND_COLOR 0xFF181818

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

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

#define PI 3.14159265359

Olivec_Canvas vc_render(float dt)
{
    Olivec_Canvas oc = olivec_canvas(pixels, WIDTH, HEIGHT, WIDTH);
    Olivec_Canvas tsodinPog = olivec_canvas(tsodinPog_pixels, tsodinPog_width, tsodinPog_height, tsodinPog_width);

    olivec_fill(oc, BACKGROUND_COLOR);

    // Triangle
    {
        triangle_angle += 0.5f*PI*dt;

        float ps[4][2];
        float uvs[4][2] = {
            {0, 0},
            {1, 0},
            {1, 1},
            {0, 1},
        };
        float len = WIDTH/4;
        for (size_t i = 0; i < 4; ++i) {
            ps[i][0] = WIDTH/2  + cosf(PI/2*i + triangle_angle)*len;
            ps[i][1] = HEIGHT/2 + sinf(PI/2*i + triangle_angle)*len;
        }
        for (size_t i = 0; i < 2; ++i) {
            int i1 = (i*2 + 0)%4;
            int i2 = (i*2 + 1)%4;
            int i3 = (i*2 + 2)%4;
            olivec_triangle3uv_bilinear(
                oc,
                ps[i1][0], ps[i1][1],
                ps[i2][0], ps[i2][1],
                ps[i3][0], ps[i3][1],
                uvs[i1][0], uvs[i1][1],
                uvs[i2][0], uvs[i2][1],
                uvs[i3][0], uvs[i3][1],
                1, 1, 1,
                tsodinPog
            );
       }
    }

    return oc;
}