threading raymarching

main.c

@@ -8,6 +8,7 @@
 #include <SDL2/SDL_gamecontroller.h>
 #include <SDL2/SDL_render.h>
 #include <SDL2/SDL_stdinc.h>
+#include <SDL2/SDL_thread.h>
 #include <SDL2/SDL_timer.h>
 #include <SDL2/SDL_video.h>
 
@@ -16,6 +17,7 @@ int exitnow = 0;
 SDL_Renderer * ren;  
 Uint32 pixels[B_INTERNAL_HEIGHT][B_INTERNAL_WIDTH];
 
+struct object white_sphere;
 
 union badpixelformat {
     struct {
@@ -93,6 +95,40 @@ int input_loop(void *ptr) {
     return 0;
 }
 
+static int raymarch_threadfn(void *data) {
+    int id = *(int *)data;
+
+    /* draw stuff */
+    /* march the rays */
+    for (int i = 0; i < B_INTERNAL_WIDTH; i++) {
+        for (int j = 0; j < B_INTERNAL_HEIGHT; j++) {
+            /* checkerboard rendering */
+            if ((i + j * B_INTERNAL_WIDTH) % B_NUM_RAYMARCH_THREADS != id) {
+                continue;
+            }
+
+            struct vec *pos = new_vec(4);
+            struct vec *dir = new_vec4(i  - B_INTERNAL_WIDTH/2, j - B_INTERNAL_HEIGHT/2, 100, 0);
+            struct ray r = (struct ray) {
+                .pos = *pos,
+                .dir = *normalise_vec_ip(dir),
+            };
+            struct pixel_info p = march(&r, &white_sphere);
+            p.col.r += p.iterations;
+            p.col.b += 255 *  p.travel_dist / 100;
+
+            //sdlb_draw_col_pixel(p.col, j, i);
+            pixels[j][i] = get_colour(&p.col);
+        //    free_vec(pos);
+        //    free_vec(dir);
+        }
+    }
+
+    free(data);
+    return 0;
+
+}
+
 
 int main(int argc, char **argv) {
 
@@ -100,53 +136,40 @@ int main(int argc, char **argv) {
     ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
     SDL_RenderSetLogicalSize(ren, B_INTERNAL_HEIGHT, B_INTERNAL_HEIGHT);
 
-    SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "2");
+    // use this to turn on antristroptic filtering
+    // SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "2");
 
     SDL_Thread *input_thread = SDL_CreateThread(input_loop, "input", (void *)NULL);
-    struct colour c = get_random_color();
+
     double elapsed;
     Uint64 start, end;
-    struct object white_sphere = new_sphere(100);
+
+    white_sphere = new_sphere(100);
 
     /* texture for drawing into */
     SDL_Rect view = {.w = B_INTERNAL_WIDTH, .h = B_INTERNAL_HEIGHT, .x = 0, .y = 0};
     SDL_Texture *texture = SDL_CreateTexture(ren, SDL_PIXELFORMAT_ARGB8888, 
             SDL_TEXTUREACCESS_STATIC, B_INTERNAL_WIDTH, B_INTERNAL_HEIGHT);
 
+    SDL_Thread ** threads = calloc(B_NUM_RAYMARCH_THREADS, sizeof(SDL_Thread *));
 
     while (!exitnow) {
         /* clear the view */
         start = SDL_GetPerformanceCounter();
- //       SDL_SetRenderDrawColor(ren, 0, 0, 0, 255);
-//        SDL_RenderClear(ren);
-//
+        SDL_RenderClear(ren);
 
-        if (SDL_GetTicks() % 800 == 0) {
-            c = get_random_color();
+        for (int i = 0; i < B_NUM_RAYMARCH_THREADS; i++) {
+            int *tid = malloc(sizeof(int));
+            *tid = i;
+            threads[i] = SDL_CreateThread(raymarch_threadfn, "raymarch", tid);
+            // tid is freed in raymarch_threadfn
         }
 
-        /* draw stuff */
-        /* march the rays */
-        for (int i = 0; i < B_INTERNAL_WIDTH; i++) {
-            for (int j = 0; j < B_INTERNAL_HEIGHT; j++) {
-                struct vec *pos = new_vec(4);
-                struct vec *dir = new_vec4(i  - B_INTERNAL_WIDTH/2, j - B_INTERNAL_HEIGHT/2, 100, 0);
-                struct ray r = (struct ray) {
-                    .pos = *pos,
-                    .dir = *normalise_vec_ip(dir),
-                };
-                struct pixel_info p = march(&r, &white_sphere);
-                p.col.r += p.iterations;
-                p.col.b += 255 *  p.travel_dist / 100;
-
-                //sdlb_draw_col_pixel(p.col, j, i);
-                pixels[j][i] = get_colour(&p.col);
-            //    free_vec(pos);
-            //    free_vec(dir);
-            }
+        for (int i = 0; i < B_NUM_RAYMARCH_THREADS; i++) {
+            int status;
+            SDL_WaitThread(threads[i], &status);
         }
 
-
         SDL_UpdateTexture(texture, &view, pixels, B_INTERNAL_WIDTH * sizeof(Uint32));
 
         SDL_RenderCopy(ren, texture, NULL, NULL);
@@ -158,7 +181,7 @@ int main(int argc, char **argv) {
         if (el > 0) {
             elapsed = 1000 / el;
         }
-        printf("framerate: %f\r", elapsed);
+        printf("\rframerate: %f", elapsed);
         fflush(stdout);
 
     }

types.h

@@ -1,10 +1,11 @@
 #ifndef TYPES_H
 #define TYPES_H
 
+#define B_NUM_RAYMARCH_THREADS 1
 #define B_WINDOW_WIDTH 800
 #define B_WINDOW_HEIGHT 600
-#define B_INTERNAL_HEIGHT 800
-#define B_INTERNAL_WIDTH 600
+#define B_INTERNAL_HEIGHT 100
+#define B_INTERNAL_WIDTH 100
 
 #include "vect.h"
 #include "main.h"