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refactor to plain x/y

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This commit is contained in:
jb 2025-07-16 23:53:19 -07:00
parent 5b8347afaa
commit 7a91b72708
6 changed files with 145 additions and 65 deletions
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1
CMakeLists.txt
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@ -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 ---

22
scripts/main.c
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@ -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;

13
scripts/swap.c Normal file
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@ -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;
}

2
scripts/swap.h Normal file
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@ -0,0 +1,2 @@
void int_swap(int* a, int* b);
void float_swap(float* a, float* b);

165
scripts/triangle.c
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@ -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);
float inv_slope_2 = (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 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);
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++) {
//draw_rect((int)triangle->points[0].x, i, 1, 1, 0xFFFF0000);
draw_line((int)x_start, x, (int)x_end, x, color);
// 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;
}
}
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);
float inv_slope_2 = (float)(triangle->points[2].x - triangle->points[1].x) / (float)(triangle->points[2].y - triangle->points[1].y);;
///////////////////////////////////////////////////////////////////////////////
// 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);
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--) {
//draw_rect((int)triangle->points[0].x, i, 1, 1, 0xFFFF0000);
draw_line((int)x_start, y, (int)x_end, y, color);
// 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;
}
}
void draw_filled_triangle(triangle_t triangle) {
// 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) {
temp = min_idx; min_idx = mid_idx; mid_idx = temp;
///////////////////////////////////////////////////////////////////////////////
// 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 (triangle.points[min_idx].y > triangle.points[max_idx].y) {
temp = min_idx; min_idx = max_idx; max_idx = temp;
if (y1 > y2) {
int_swap(&y1, &y2);
int_swap(&x1, &x2);
}
if (triangle.points[mid_idx].y > triangle.points[max_idx].y) {
temp = mid_idx; mid_idx = max_idx; max_idx = temp;
if (y0 > y1) {
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) {
fill_flat_bottom_triangle(&triangle, color);
} else if (triangle.points[min_idx].y == triangle.points[mid_idx].y) {
fill_flat_top_triangle(&triangle, color);
// 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);
}
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) {
temp = min_idx; min_idx = mid_idx; mid_idx = temp;
// 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) {
temp = min_idx; min_idx = max_idx; max_idx = temp;
if (y1 > y2) {
int_swap(&y1, &y2);
int_swap(&x1, &x2);
}
if (triangle.points[mid_idx].y > triangle.points[max_idx].y) {
temp = mid_idx; mid_idx = max_idx; max_idx = temp;
if (y0 > y1) {
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
}
*/
}

7
scripts/triangle.h
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@ -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_textured_triangle(triangle_t triangle, uint32_t* texture);
void draw_filled_triangle(int x0, int y0, int x1, int y1, int x2, int y2, color_t color);
void draw_textured_triangle(int x0, int y0, int x1, int y1, int x2, int y2, uint32_t* texture);
#endif