added starfield

[vrtris] / src / starfield.c

diff --git a/src/starfield.c b/src/starfield.c
new file mode 100644 (file)
index 0000000..6f7b9ae
--- /dev/null
+++ b/src/starfield.c
@@ -0,0 +1,123 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <cgmath/cgmath.h>
+#include <imago2.h>
+#include "opengl.h"
+#include "game.h"
+#include "logger.h"
+
+static unsigned int tex_bolt, tex_star;
+static float star_speed = 100.0f;
+static float star_depth = 1000.0f;
+static float star_size = 0.35f;
+
+#define STAR_ZOFFS     100.0f
+#define STAR_COUNT     4096
+static cgm_vec3 star[STAR_COUNT];
+static float star_lenxy[STAR_COUNT];
+
+int init_starfield(void)
+{
+       int i;
+       float width;
+
+       if(!(tex_star = img_gltexture_load("data/pimg.png"))) {
+               error_log("failed to load star texture\n");
+               return -1;
+       }
+       if(!(tex_bolt = img_gltexture_load("data/bolt.png"))) {
+               error_log("failed to load star tail texture\n");
+               return -1;
+       }
+
+       width = star_depth / 4.0f;
+       for(i=0; i<STAR_COUNT; i++) {
+               float x = (2.0f * rand() / RAND_MAX) - 1.0;
+               float y = (2.0f * rand() / RAND_MAX) - 1.0;
+               float z = (float)rand() / RAND_MAX;
+
+               cgm_vcons(star + i, x * width, y * width, z * star_depth);
+               star_lenxy[i] = sqrt(star[i].x * star[i].x + star[i].y * star[i].y);
+       }
+       return 0;
+}
+
+void draw_starfield(void)
+{
+       int i;
+       cgm_vec3 pos;
+       float x, y, z, t;
+       float x0, y0, x1, y1;
+       float theta, sz;
+
+       glPushAttrib(GL_ENABLE_BIT);
+       glDisable(GL_DEPTH_TEST);
+       glDisable(GL_LIGHTING);
+       glDisable(GL_CULL_FACE);
+       glEnable(GL_BLEND);
+       glBlendFunc(GL_SRC_ALPHA, GL_ONE);
+
+       glEnable(GL_TEXTURE_2D);
+       glBindTexture(GL_TEXTURE_2D, tex_bolt);
+
+       glBegin(GL_QUADS);
+       for(i=0; i<STAR_COUNT; i++) {
+               pos = star[i];
+               z = fmod(pos.z + time_msec * star_speed / 1000.0f, star_depth);
+               t = z / star_depth;
+               pos.z = z - star_depth + STAR_ZOFFS;
+
+               theta = atan2(pos.y / star_lenxy[i], pos.x / star_lenxy[i]);
+
+               y = -star_size;
+               x = 0;
+
+               x0 = x * cos(theta) - y * sin(theta);
+               y0 = x * sin(theta) + y * cos(theta);
+
+               y = star_size;
+
+               x1 = x * cos(theta) - y * sin(theta);
+               y1 = x * sin(theta) + y * cos(theta);
+
+               x0 += pos.x;
+               x1 += pos.x;
+               y0 += pos.y;
+               y1 += pos.y;
+
+               glColor4f(1, 1, 1, t);
+               glTexCoord2f(0, 1);
+               glVertex3f(x0, y0, pos.z);
+               glTexCoord2f(1, 1);
+               glVertex3f(x1, y1, pos.z);
+               glTexCoord2f(1, 0);
+               glVertex3f(x1, y1, pos.z - star_size * 16.0);
+               glTexCoord2f(0, 0);
+               glVertex3f(x0, y0, pos.z - star_size * 16.0);
+       }
+       glEnd();
+
+       glBindTexture(GL_TEXTURE_2D, tex_star);
+       sz = star_size * 4.0f;
+       glBegin(GL_QUADS);
+       for(i=0; i<STAR_COUNT; i++) {
+               pos = star[i];
+               z = fmod(pos.z + time_msec * star_speed / 1000.0f, star_depth);
+               t = z / star_depth;
+               pos.z = z - star_depth + STAR_ZOFFS;
+
+               glColor4f(1, 1, 1, t);
+               glTexCoord2f(0, 0);
+               glVertex3f(pos.x - sz, pos.y - sz, pos.z);
+               glTexCoord2f(1, 0);
+               glVertex3f(pos.x + sz, pos.y - sz, pos.z);
+               glTexCoord2f(1, 1);
+               glVertex3f(pos.x + sz, pos.y + sz, pos.z);
+               glTexCoord2f(0, 1);
+               glVertex3f(pos.x - sz, pos.y + sz, pos.z);
+       }
+       glEnd();
+
+       glPopAttrib();
+}