Added files

1 files changed, 139 insertions, 0 deletions

diff --git a/src/triangle.h b/src/triangle.h
new file mode 100644
index 0000000..9ef4de4
--- /dev/null
+++ b/src/triangle.h
@@ -0,0 +1,139 @@
+#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