Move rendering logic into camera module

include/camera.h

@@ -1,6 +1,8 @@
 #ifndef CAMERA_H
 #define CAMERA_H
 
+#include "img.h"
+#include "obj.h"
 #include "vec3.h"
 
 #include <stdint.h>
@@ -8,10 +10,15 @@
 typedef struct {
 	vec3_t pos;
 	vec3_t pix_origin, x_step, y_step;
+	uint32_t img_width, img_height;
 } camera_t;
 
 camera_t camera_init(
     vec3_t pos, double focal_len, double viewport_height, uint32_t img_width,
     uint32_t img_height);
 
+void camera_render(
+    const camera_t *camera, const obj_t *scene, unsigned scene_count,
+    img_t *img_out);
+
 #endif