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#include "fixed.h"
#include "defs.h"
#include "vertex.h"
#include "plane.h"
#include "color.h"
#include <math.h>
#ifndef TRIANGLE_H
#define TRIANGLE_H
typedef struct TRIANGLE {
int v0;
int v1;
int v2;
COLOR color;
} TRIANGLE;
static inline TRIANGLE createTriangle(int v0, int v1, int v2, COLOR color) {
// Create a triangle from data
TRIANGLE temp;
temp.v0 = v0;
temp.v1 = v1;
temp.v2 = v2;
temp.color = color;
return temp;
}
static inline VERTEX computeNormal(VERTEX *vertices, TRIANGLE *triangle) {
// Use cross product to compute a normal vector to a triangle
VERTEX normal, v1, v2;
// Compute vectors for cross product
v1.x = (vertices + triangle->v1)->x - (vertices + triangle->v0)->x;
v1.y = (vertices + triangle->v1)->y - (vertices + triangle->v0)->y;
v1.z = (vertices + triangle->v1)->z - (vertices + triangle->v0)->z;
v2.x = (vertices + triangle->v2)->x - (vertices + triangle->v0)->x;
v2.y = (vertices + triangle->v2)->y - (vertices + triangle->v0)->y;
v2.z = (vertices + triangle->v2)->z - (vertices + triangle->v0)->z;
// Compute cross product
normal.x = fixed_multiply(v1.y, v2.z) - fixed_multiply(v1.z, v2.y);
normal.y = fixed_multiply(v1.z, v2.x) - fixed_multiply(v1.x, v2.z);
normal.z = fixed_multiply(v1.x, v2.y) - fixed_multiply(v1.y, v2.x);
return normal;
}
static inline void drawTriangle(POINT *v1, POINT *v2, POINT *v3, COLOR *clr, SDL_Renderer *renderer) {
// Draw a triangle to screen from data
int x1, x2, x3, y1, y2, y3;
SDL_SetRenderDrawColor(renderer, clr->red, clr->green, clr->blue, 255);
x1 = (v1->x >> FIX_SHIFT) + WINDOW_WIDTH / 2;
x2 = (v2->x >> FIX_SHIFT) + WINDOW_WIDTH / 2;
x3 = (v3->x >> FIX_SHIFT) + WINDOW_WIDTH / 2;
y1 = WINDOW_HEIGHT / 2 - (v1->y >> FIX_SHIFT) - 1;
y2 = WINDOW_HEIGHT / 2 - (v2->y >> FIX_SHIFT) - 1;
y3 = WINDOW_HEIGHT / 2 - (v3->y >> FIX_SHIFT) - 1;
SDL_RenderDrawLine(renderer, x1, y1, x2, y2);
SDL_RenderDrawLine(renderer, x1, y1, x3, y3);
SDL_RenderDrawLine(renderer, x2, y2, x3, y3);
}
static inline void fillBottomFlatTriangle(POINT *v1, POINT *v2, POINT *v3, COLOR *clr, SDL_Renderer *renderer) {
// Ported from sunshine2k.de
SDL_SetRenderDrawColor(renderer, clr->red, clr->green, clr->blue, 255);
FIXED iSlope1 = fixed_divide(v2->x - v1->x, v2->y - v1->y);
FIXED iSlope2 = fixed_divide(v3->x - v1->x, v3->y - v1->y);
FIXED curx1 = v1->x;
FIXED curx2 = curx1;
int scanline;
for (int scanlineY = ((v1->y + (1 << FIX_SHIFT)) >> FIX_SHIFT); scanlineY <= (v2->y >> FIX_SHIFT); scanlineY++) {
scanline = WINDOW_HEIGHT / 2 - scanlineY - 1;
SDL_RenderDrawLine(renderer, ((curx1 >> FIX_SHIFT) + WINDOW_WIDTH / 2),
scanline, ((curx2 >> FIX_SHIFT) + WINDOW_WIDTH / 2), scanline
);
curx1 += iSlope1;
curx2 += iSlope2;
}
}
static inline void fillTopFlatTriangle(POINT *v1, POINT *v2, POINT *v3, COLOR *clr, SDL_Renderer *renderer) {
// Ported from sunshine2k.de
SDL_SetRenderDrawColor(renderer, clr->red, clr->green, clr->blue, 255);
FIXED iSlope1 = fixed_divide(v3->x - v1->x, v3->y - v1->y);
FIXED iSlope2 = fixed_divide(v3->x - v2->x, v3->y - v2->y);
FIXED curx1 = v3->x;
FIXED curx2 = curx1;
int scanline;
for (int scanlineY = ((v3->y - (1 << FIX_SHIFT)) >> FIX_SHIFT); scanlineY > (v1->y >> FIX_SHIFT); scanlineY--) {
scanline = WINDOW_HEIGHT / 2 - scanlineY - 1;
SDL_RenderDrawLine(renderer, ((curx1 >> FIX_SHIFT) + WINDOW_WIDTH / 2),
scanline, ((curx2 >> FIX_SHIFT) + WINDOW_WIDTH / 2), scanline
);
curx1 -= iSlope1;
curx2 -= iSlope2;
}
}
static inline void drawFilledTriangle(POINT *v1, POINT *v2, POINT *v3, COLOR *clr, SDL_Renderer *renderer) {
// Draw a filled triangle at points
// Sort the vertex points
POINT p1, p2, p3;
p1 = *v1;
p2 = *v2;
p3 = *v3;
if (p1.y > p2.y) {
swapPoint(&p1, &p2);
}
if (p1.y > p3.y) {
swapPoint(&p1, &p3);
}
if (p2.y > p3.y) {
swapPoint(&p2, &p3);
}
// Check if bottom of triangle is flat
if (p2.y == p3.y) {
fillBottomFlatTriangle(&p1, &p2, &p3, clr, renderer);
}
// Check if top of triangle is flat
else if (p1.y == p2.y) {
fillTopFlatTriangle(&p1, &p2, &p3, clr, renderer);
}
else {
// General case where neither top or bottom is flat
POINT p4 = createPoint(
p1.x + fixed_multiply(fixed_divide(p2.y - p1.y, p3.y - p1.y), (p3.x - p1.x))
,p2.y
);
fillBottomFlatTriangle(&p1, &p2, &p4, clr, renderer);
fillTopFlatTriangle(&p2, &p4, &p3, clr, renderer);
}
}
#endif // TRIANGLE_H
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