#include "triangle.h" #include #include #include "display.h" // TODO: Create implementation for triangle.h functions int compare_vec2_t(const void* a, const void* b) { const int_vec2_t* arg1 = (const int_vec2_t*)a; const int_vec2_t* arg2 = (const int_vec2_t*)b; if (arg1->y < arg2->y) return -1; if (arg1->y > arg2->y) return 1; return 0; } #define FUNC (int)ceilf #define FUNC2 (int)floorf uint32_t invert_rgb(uint32_t color) { uint32_t a = color & 0xFF000000; // Alpha channel uint32_t rgb = color & 0x00FFFFFF; // RGB channels rgb = ~rgb & 0x00FFFFFF; // Invert RGB only return a | rgb; } void draw_triangle(triangle_t triangle, uint32_t color) { draw_line(triangle.points[0].x, triangle.points[0].y, triangle.points[1].x, triangle.points[1].y, color); draw_line(triangle.points[1].x, triangle.points[1].y, triangle.points[2].x, triangle.points[2].y, color); draw_line(triangle.points[2].x, triangle.points[2].y, triangle.points[0].x, triangle.points[0].y, color); } /////////////////////////////////////////////////////////////////////////////// // Draw a filled a triangle with a flat bottom /////////////////////////////////////////////////////////////////////////////// // // (x0,y0) // / \ // / \ // / \ // / \ // / \ // (x1,y1)------(x2,y2) // /////////////////////////////////////////////////////////////////////////////// void fill_flat_bottom_triangle(int x0, int y0, int x1, int y1, int x2, int y2, uint32_t color) { // Find the two slopes (two triangle legs) float inv_slope_1 = (float)(x1 - x0) / (y1 - y0); float inv_slope_2 = (float)(x2 - x0) / (y2 - y0); // Start x_start and x_end from the top vertex (x0,y0) float x_start = x0; float x_end = x0; // Loop all the scanlines from top to bottom for (int y = y0; y <= y2; y++) { draw_line(x_start, y, x_end, y, color); x_start += inv_slope_1; x_end += inv_slope_2; } } /////////////////////////////////////////////////////////////////////////////// // Draw a filled a triangle with a flat top /////////////////////////////////////////////////////////////////////////////// // // (x0,y0)------(x1,y1) // \ / // \ / // \ / // \ / // \ / // (x2,y2) // /////////////////////////////////////////////////////////////////////////////// void fill_flat_top_triangle(int x0, int y0, int x1, int y1, int x2, int y2, uint32_t color) { // Find the two slopes (two triangle legs) float inv_slope_1 = (float)(x2 - x0) / (y2 - y0); float inv_slope_2 = (float)(x2 - x1) / (y2 - y1); // Start x_start and x_end from the bottom vertex (x2,y2) float x_start = x2; float x_end = x2; // Loop all the scanlines from bottom to top for (int y = y2; y >= y0; y--) { draw_line(x_start, y, x_end, y, color); x_start -= inv_slope_1; x_end -= inv_slope_2; } } /////////////////////////////////////////////////////////////////////////////// // Draw a filled triangle with the flat-top/flat-bottom method // We split the original triangle in two, half flat-bottom and half flat-top /////////////////////////////////////////////////////////////////////////////// // // (x0,y0) // / \ // / \ // / \ // / \ // / \ // (x1,y1)------(Mx,My) // \_ \ // \_ \ // \_ \ // \_ \ // \ \ // \_ \ // \_\ // \ // (x2,y2) // /////////////////////////////////////////////////////////////////////////////// void draw_filled_triangle(int x0, int y0, int x1, int y1, int x2, int y2, uint32_t color) { // We need to sort the vertices by y-coordinate ascending (y0 < y1 < y2) if (y0 > y1) { int_swap(&y0, &y1); int_swap(&x0, &x1); } if (y1 > y2) { int_swap(&y1, &y2); int_swap(&x1, &x2); } if (y0 > y1) { int_swap(&y0, &y1); int_swap(&x0, &x1); } if (y1 == y2) { // Draw flat-bottom triangle fill_flat_bottom_triangle(x0, y0, x1, y1, x2, y2, color); } else if (y0 == y1) { // Draw flat-top triangle fill_flat_top_triangle(x0, y0, x1, y1, x2, y2, color); } else { // Calculate the new vertex (Mx,My) using triangle similarity int My = y1; int Mx = (((x2 - x0) * (y1 - y0)) / (y2 - y0)) + x0; // Draw flat-bottom triangle fill_flat_bottom_triangle(x0, y0, x1, y1, Mx, My, color); // Draw flat-top triangle fill_flat_top_triangle(x1, y1, Mx, My, x2, y2, color); } } vec3_t barycentric_weights(vec2_t a, vec2_t b, vec2_t c, vec2_t p) { // Find the vectors between the vertices ABC and point p vec2_t ac = vec2_subtract(c, a); vec2_t ab = vec2_subtract(b, a); vec2_t ap = vec2_subtract(p, a); vec2_t pc = vec2_subtract(c, p); vec2_t pb = vec2_subtract(b, p); // Compute the area of the full parallegram/triangle ABC using 2D cross product float area_parallelogram_abc = (ac.x * ab.y - ac.y * ab.x); // || AC x AB || // Alpha is the area of the small parallelogram/triangle PBC divided by the area of the full parallelogram/triangle ABC float alpha = (pc.x * pb.y - pc.y * pb.x) / area_parallelogram_abc; // Beta is the area of the small parallelogram/triangle APC divided by the area of the full parallelogram/triangle ABC float beta = (ac.x * ap.y - ac.y * ap.x) / area_parallelogram_abc; // Weight gamma is easily found since barycentric coordinates always add up to 1.0 float gamma = 1 - alpha - beta; vec3_t weights = { alpha, beta, gamma }; return weights; } //////////////////////////// // Function to draw textue at x/y using interpolation void draw_texel( int x, int y, uint32_t* texture, vec2_t point_a, vec2_t point_b, vec2_t point_c, float u0, float v0, float u1, float v1, float u2, float v2) { vec2_t point_p = { x, y }; vec3_t weights = barycentric_weights(point_a, point_b, point_c, point_p); float alpha = weights.x; float beta = weights.y; float gamma = weights.z; // Perform the interpolation of all U and V values using barycentric weights float interpolated_u = (u0) * alpha + (u1) * beta + (u2) * gamma; float interpolated_v = (v0) * alpha + (v1) * beta + (v2) * gamma; // Map the UV coordinate to the full texture width and height int tex_x = abs((int)(interpolated_u * texture_width)); int tex_y = abs((int)(interpolated_v * texture_height)); draw_pixel(x, y, texture[(texture_width * tex_y) + tex_x]); } void draw_textured_triangle( int x0, int y0, float u0, float v0, int x1, int y1, float u1, float v1, int x2, int y2, float u2, float v2, uint32_t* texture) { // sort by y int temp = 0, min_idx = 0, mid_idx = 1, max_idx = 2; // We need to sort the vertices by y-coordinate ascending (y0 < y1 < y2) if (y0 > y1) { int_swap(&y0, &y1); int_swap(&x0, &x1); } if (y1 > y2) { int_swap(&y1, &y2); int_swap(&x1, &x2); } if (y0 > y1) { int_swap(&y0, &y1); int_swap(&x0, &x1); } // create vector points after sorting vertices vec2_t point_a = { x0, y0 }; vec2_t point_b = { x1, y1 }; vec2_t point_c = { x2, y2 }; // FLAT BOTTOM float inv_slope_1 = 0; float inv_slope_2 = 0; if (y1 - y0 != 0) inv_slope_1 = (float)(x1 - x0) / abs(y1 - y0); if (y2 - y0 != 0) inv_slope_2 = (float)(x2 - x0) / abs(y2 - y0); if (y1 - y0 != 0) { for (int y = y0; y <= y1; y++) { int x_start = x1 + (y - y1) * inv_slope_1; int x_end = x0 + (y - y0) * inv_slope_2; if (x_end < x_start) { int_swap(&x_start, &x_end); } for (int x = x_start; x < x_end; x++) { // draw pixel with color from texture //draw_pixel(x, y, (x % 2 == 0 && y % 2 == 0) ? 0xFF00FF00 : 0xFF000000); draw_texel(x, y, texture, point_a, point_b, point_c, u0, v0, u1, v1, u2, v2); } } } // FLAT TOP inv_slope_1 = 0; inv_slope_2 = 0; if (y2 - y1 != 0) inv_slope_1 = (float)(x2 - x1) / abs(y2 - y1); if (y2 - y0 != 0) inv_slope_2 = (float)(x2 - x0) / abs(y2 - y0); if (y2 - y1 != 0) { for (int y = y1; y <= y2; y++) { int x_start = x1 + (y - y1) * inv_slope_1; int x_end = x0 + (y - y0) * inv_slope_2; if (x_end < x_start) { int_swap(&x_start, &x_end); } for (int x = x_start; x < x_end; x++) { // draw pixel with color from texture //draw_pixel(x, y, (x % 2 == 0 && y % 2 == 0) ? 0xFF00FF00 : 0xFF000000); draw_texel(x, y, texture, point_a, point_b, point_c, u0, v0, u1, v1, u2, v2); } } } }