diff --git a/src/main.cpp b/src/main.cpp index 02beea8..715de08 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -16,24 +16,24 @@ const TGAColor purple = TGAColor(150, 47, 254, 255); const int windowHeight = 800; const int windowWidth = 800; -void line(int x0, int y0, int x1, int y1, TGAImage &image, TGAColor color) { +void line(Vec2i t0, Vec2i t1, TGAImage &image, TGAColor color) { bool steep = false; // if the line is steep, we transpose the image. - if (abs(x0 - x1) < abs(y0 - y1)) { - swap(x0, y0); - swap(x1, y1); + if (abs(t0.x - t1.x) < abs(t0.y - t1.y)) { + swap(t0.x, t0.y); + swap(t1.x, t1.y); steep = true; } // Make it left to right. - if (x0 > x1) { - swap(x0, x1); - swap(y0, y1); + if (t0.x > t1.x) { + swap(t0.x, t1.x); + swap(t0.y, t1.y); } - for (int x = x0; x <= x1; x++) { - float t = (x - x0) / (float)(x1 - x0); - int y = y0 * (1.0 - t) + y1 * t; + for (int x = t0.x; x <= t1.x; x++) { + float t = (x - t0.x) / (float)(t1.x - t0.x); + int y = t0.y * (1.0 - t) + t1.y * t; if (steep) { image.set(y, x, color); // if transposed, de-transpose. } else { @@ -42,30 +42,59 @@ void line(int x0, int y0, int x1, int y1, TGAImage &image, TGAColor color) { } } -void triangle(int x1, int y1, int x2, int y2, int x3, int y3, TGAImage &image, - TGAColor colour) { - line(x1, y1, x2, y2, image, colour); - line(x2, y2, x3, y3, image, colour); - line(x3, y3, x1, y1, image, colour); +void triangle(Vec2i t0, Vec2i t1, Vec2i t2, TGAImage &image, TGAColor colour) { + // Sorting the y-coördinates + if (t0.y > t1.y) + swap(t0, t1); + if (t0.y > t2.y) + swap(t0, t2); + if (t1.y > t2.y) + swap(t1, t2); + + // Cut the triangle horizontally to render the bottom half. + int totalHeight = t2.y - t0.y; + for (int y = t0.y; y <= t1.y; y++) { + int segmentHeight = t1.y - t0.y + 1; + float alpha = (float)(y - t0.y) / totalHeight; + float beta = (float)(y - t0.y) / segmentHeight; + + Vec2i A = t0 + (t2 - t0) * alpha; + Vec2i B = t0 + (t1 - t0) * beta; + + if (A.x > B.x) + swap(A, B); + for (int j = A.x; j <= B.x; j++) { + image.set(j, y, colour); + } + } + + // Render the top half. + for (int y = t1.y; y < t2.y; y++) { + int segmentHeight = t2.y - t1.y + 1; + float alpha = (float)(y - t0.y) / totalHeight; + float beta = (float)(y - t1.y) / segmentHeight; + + Vec2i A = t0 + (t2 - t0) * alpha; + Vec2i B = t1 + (t2 - t1) * beta; + + if (A.x > B.x) + swap(A, B); + for (int j = A.x; j <= B.x; j++) { + image.set(j, y, colour); + } + } } int main(int argc, char **argv) { TGAImage image(windowWidth, windowHeight, TGAImage::RGB); - // Initialise random. - srand(time(NULL)); - int x1 = rand() % (windowWidth + 1); - int x2 = rand() % (windowWidth + 1); - int x3 = rand() % (windowWidth + 1); + Vec2i t0[3] = {Vec2i(20, 140), Vec2i(100, 320), Vec2i(140, 160)}; + Vec2i t1[3] = {Vec2i(360, 100), Vec2i(300, 2), Vec2i(140, 360)}; + Vec2i t2[3] = {Vec2i(360, 300), Vec2i(240, 320), Vec2i(260, 360)}; - int y1 = rand() % (windowHeight + 1); - int y2 = rand() % (windowHeight + 1); - int y3 = rand() % (windowHeight + 1); - - // Random colours. - TGAColor colours[] = {white, purple, red}; - - triangle(x1, y1, x2, y2, x3, y3, image, colours[(rand() % 3) - 1]); + triangle(t0[0], t0[1], t0[2], image, red); + triangle(t1[0], t1[1], t1[2], image, white); + triangle(t2[0], t2[1], t2[2], image, purple); image.write_tga_file("output.tga");