refactor to plain x/y

CMakeLists.txt

@@ -12,6 +12,7 @@ add_executable(${PROJECT_NAME} scripts/main.c
         scripts/triangle.c
         scripts/light.c
         scripts/texture.c
+        scripts/swap.c
         scripts/display.c)
 
 # --- SDL2 SETUP ---

scripts/main.c

@@ -152,9 +152,9 @@ void update(void) {
 
     previous_frame_time = SDL_GetTicks();
 
-    //mesh.rotation.y += 0.01f;
+    mesh.rotation.y += 0.01f;
     mesh.rotation.x -= 0.01f;
-    //mesh.rotation.z += 0.01f;
+    mesh.rotation.z += 0.01f;
 
     //mesh.translation.x += 0.004f;
     mesh.translation.z = 5.0f;
@@ -317,17 +317,27 @@ void render(void) {
                 draw_rect(triangle.points[2].x, triangle.points[2].y, 3, 3, 0xFFFFFF00);
                 break;
             case RENDER_FILL_TRIANGLE:
-                draw_filled_triangle(triangle);
+                draw_filled_triangle(
+                    triangle.points[0].x, triangle.points[0].y, // vertex A
+                    triangle.points[1].x, triangle.points[1].y, // vertex B
+                    triangle.points[2].x, triangle.points[2].y,
+                    triangle.color
+                );
                 break;
             case RENDER_FILL_TRIANGLE_LINE:
-                draw_filled_triangle(triangle);
+                draw_filled_triangle(
+                    triangle.points[0].x, triangle.points[0].y, // vertex A
+                    triangle.points[1].x, triangle.points[1].y, // vertex B
+                    triangle.points[2].x, triangle.points[2].y, // vertex C
+                    triangle.color
+                );
                 draw_triangle(triangle, 0xff0000ff);
                 break;
             case RENDER_TEXTURED:
-                draw_textured_triangle(triangle, mesh_texture);
+                //draw_textured_triangle(triangle, mesh_texture);
                 break;
             case RENDER_TEXTURED_LINE:
-                draw_textured_triangle(triangle, mesh_texture);
+                //draw_textured_triangle(triangle, mesh_texture);
                 draw_triangle(triangle, 0xff0000ff);
             default:
                 break;

scripts/swap.c

@@ -0,0 +1,13 @@
+#include "swap.h"
+
+void int_swap(int* a, int* b) {
+    int tmp = *a;
+    *a = *b;
+    *b = tmp;
+}
+
+void float_swap(float* a, float* b) {
+    float tmp = *a;
+    *a = *b;
+    *b = tmp;
+}

scripts/swap.h

@@ -0,0 +1,2 @@
+void int_swap(int* a, int* b);
+void float_swap(float* a, float* b);

scripts/triangle.c

@@ -1,5 +1,6 @@
 #include "triangle.h"
 
+#include <stdio.h>
 #include <math.h>
 
 #include "display.h"
@@ -23,94 +24,145 @@ uint32_t invert_rgb(uint32_t color) {
     return a | rgb;
 }
 
-void fill_flat_bottom_triangle(const triangle_t* triangle, color_t color) {
+///////////////////////////////////////////////////////////////////////////////
-    float inv_slope_1 = (float)(triangle->points[1].x - triangle->points[0].x) / (float)(triangle->points[1].y - triangle->points[0].y);
+// Draw a filled a triangle with a flat bottom
-    float inv_slope_2 = (float)(triangle->points[2].x - triangle->points[0].x) / (float)(triangle->points[2].y - triangle->points[0].y);;
+///////////////////////////////////////////////////////////////////////////////
+//
+//        (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);
 
-    float x_start = (float)triangle->points[0].x, x_end = (float)triangle->points[0].x;
+    // Start x_start and x_end from the top vertex (x0,y0)
+    float x_start = x0;
+    float x_end = x0;
 
-    for (int x = triangle->points[0].y; x <= triangle->points[2].y; x++) {
+    // Loop all the scanlines from top to bottom
-        //draw_rect((int)triangle->points[0].x, i, 1, 1, 0xFFFF0000);
+    for (int y = y0; y <= y2; y++) {
-        draw_line((int)x_start, x, (int)x_end, x, color);
+        draw_line(x_start, y, x_end, y, color);
         x_start += inv_slope_1;
         x_end += inv_slope_2;
     }
 }
 
-void fill_flat_top_triangle(const triangle_t* triangle, color_t color) {
+///////////////////////////////////////////////////////////////////////////////
-    float inv_slope_1 = (float)(triangle->points[2].x - triangle->points[0].x) / (float)(triangle->points[2].y - triangle->points[0].y);
+// Draw a filled a triangle with a flat top
-    float inv_slope_2 = (float)(triangle->points[2].x - triangle->points[1].x) / (float)(triangle->points[2].y - triangle->points[1].y);;
+///////////////////////////////////////////////////////////////////////////////
+//
+//  (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);
 
-    float x_start = (float)triangle->points[2].x, x_end = (float)triangle->points[2].x;
+    // Start x_start and x_end from the bottom vertex (x2,y2)
+    float x_start = x2;
+    float x_end = x2;
 
-    for (int y = triangle->points[2].y; y >= triangle->points[0].y; y--) {
+    // Loop all the scanlines from bottom to top
-        //draw_rect((int)triangle->points[0].x, i, 1, 1, 0xFFFF0000);
+    for (int y = y2; y >= y0; y--) {
-        draw_line((int)x_start, y, (int)x_end, y, color);
+        draw_line(x_start, y, x_end, y, color);
         x_start -= inv_slope_1;
         x_end -= inv_slope_2;
     }
 }
 
-void draw_filled_triangle(triangle_t triangle) {
+///////////////////////////////////////////////////////////////////////////////
-    // sort by y
+// Draw a filled triangle with the flat-top/flat-bottom method
-    int temp = 0, min_idx = 0, mid_idx = 1, max_idx = 2;
+// We split the original triangle in two, half flat-bottom and half flat-top
-
+///////////////////////////////////////////////////////////////////////////////
-    if (triangle.points[min_idx].y > triangle.points[mid_idx].y) {
+//
-        temp = min_idx; min_idx = mid_idx; mid_idx = temp;
+//          (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 (triangle.points[min_idx].y > triangle.points[max_idx].y) {
+    if (y1 > y2) {
-        temp = min_idx; min_idx = max_idx; max_idx = temp;
+        int_swap(&y1, &y2);
+        int_swap(&x1, &x2);
     }
-    if (triangle.points[mid_idx].y > triangle.points[max_idx].y) {
+    if (y0 > y1) {
-        temp = mid_idx; mid_idx = max_idx; max_idx = temp;
+        int_swap(&y0, &y1);
+        int_swap(&x0, &x1);
     }
 
-    color_t color = triangle.color ? triangle.color : 0xFF00FF00; // Default to 0xFF00FF00 if not setr; // Default color if not set
+    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;
 
-    if (triangle.points[mid_idx].y == triangle.points[max_idx].y) {
+        // Draw flat-bottom triangle
-        fill_flat_bottom_triangle(&triangle, color);
+        fill_flat_bottom_triangle(x0, y0, x1, y1, Mx, My, color);
-    } else if (triangle.points[min_idx].y == triangle.points[mid_idx].y) {
+
-        fill_flat_top_triangle(&triangle, color);
+        // Draw flat-top triangle
+        fill_flat_top_triangle(x1, y1, Mx, My, x2, y2, color);
     }
-
-
-    int_vec2_t midpoint;
-    midpoint.y = triangle.points[mid_idx].y;
-    midpoint.x = (((triangle.points[max_idx].x - triangle.points[min_idx].x) * (triangle.points[mid_idx].y - triangle.points[min_idx].y)) / (triangle.points[max_idx].y - triangle.points[min_idx].y)) + triangle.points[min_idx].x;
-
-    triangle_t flat_top, flat_bottom;
-
-    flat_bottom.points[0] = triangle.points[min_idx];
-    flat_bottom.points[1] = triangle.points[mid_idx];
-    flat_bottom.points[2] = midpoint;
-
-    flat_top.points[0] = triangle.points[mid_idx];
-    flat_top.points[1] = midpoint;
-    flat_top.points[2] = triangle.points[max_idx];
-
-    fill_flat_bottom_triangle(&flat_bottom, color);
-    fill_flat_top_triangle(&flat_top, (color));
-
 }
 
-void draw_textured_triangle(triangle_t triangle, uint32_t* texture) {
+void draw_textured_triangle(int x0, int y0, int x1, int y1, int x2, int y2, uint32_t* texture) {
     // sort by y
     int temp = 0, min_idx = 0, mid_idx = 1, max_idx = 2;
 
-    if (triangle.points[min_idx].y > triangle.points[mid_idx].y) {
+    // We need to sort the vertices by y-coordinate ascending (y0 < y1 < y2)
-        temp = min_idx; min_idx = mid_idx; mid_idx = temp;
+    if (y0 > y1) {
+        int_swap(&y0, &y1);
+        int_swap(&x0, &x1);
     }
-    if (triangle.points[min_idx].y > triangle.points[max_idx].y) {
+    if (y1 > y2) {
-        temp = min_idx; min_idx = max_idx; max_idx = temp;
+        int_swap(&y1, &y2);
+        int_swap(&x1, &x2);
     }
-    if (triangle.points[mid_idx].y > triangle.points[max_idx].y) {
+    if (y0 > y1) {
-        temp = mid_idx; mid_idx = max_idx; max_idx = temp;
+        int_swap(&y0, &y1);
+        int_swap(&x0, &x1);
     }
 
     float inv_slope_1 = 0;
     float inv_slope_2 = 0;
 
-    if (triangle.points[mid_idx].y - triangle.points[min_idx].y != 0) {
+    /*if (triangle.points[mid_idx].y - triangle.points[min_idx].y != 0) {
         inv_slope_1 = (float)(triangle.points[mid_idx].x - triangle.points[min_idx].x) / fabsf(triangle.points[mid_idx].y - triangle.points[min_idx].y);
     }
 
@@ -121,6 +173,7 @@ void draw_textured_triangle(triangle_t triangle, uint32_t* texture) {
     for (int y = triangle.points[min_idx].y; y <= triangle.points[mid_idx].y; y++) {
         //float x_start = triangle
     }
+    */
 
 
 }

scripts/triangle.h

@@ -4,6 +4,7 @@
 #include <stdint.h>
 
 #include "texture.h"
+#include "swap.h"
 #include "vector.h"
 #include "texture.h"
 
@@ -25,14 +26,14 @@ typedef struct {
 } int_vec2_t;
 
 typedef struct {
-    int_vec2_t points[3];
+    vec2_t points[3];
     tex2_t texcoords[3];
     color_t color;
     float average_depth;
 } triangle_t;
 
-void draw_filled_triangle(triangle_t triangle);
+void draw_filled_triangle(int x0, int y0, int x1, int y1, int x2, int y2, color_t color);
-void draw_textured_triangle(triangle_t triangle, uint32_t* texture);
+void draw_textured_triangle(int x0, int y0, int x1, int y1, int x2, int y2, uint32_t* texture);
 
 
 #endif