Added image-based lighting with HDR images.

environment.cpp

@@ -0,0 +1,38 @@
+#include <cmath>
+
+#include <glm/glm.hpp>
+#include <glm/gtc/constants.hpp>
+
+#include "environment.hpp"
+
+using glm::vec2;
+using glm::acos;
+using glm::pi;
+
+vec3 Environment::get_color(Ray & r) {
+  float _r;
+  vec2 tex_coord;
+  BYTE * bits;
+  FIRGBF * pixel;
+  unsigned int pitch;
+
+  if (m_texture == NULL)
+    return m_bckg_color;
+  else {
+    if (!m_probe) {
+      tex_coord = vec2((1.0f + atan2(r.m_direction.x, -r.m_direction.z) / pi<float>()) / 2.0f, acos(r.m_direction.y) / pi<float>());
+      tex_coord = vec2(tex_coord.x, 1.0f - tex_coord.y);
+    } else {
+      _r = (1.0f / pi<float>()) * acos(r.m_direction.z) / glm::sqrt((r.m_direction.x * r.m_direction.x) + (r.m_direction.y * r.m_direction.y));
+      tex_coord = vec2(r.m_direction.x * _r, r.m_direction.y * _r);
+      tex_coord += vec2(1.0f, 1.0f);
+      tex_coord /= 2.0f;
+    }
+
+    tex_coord *= vec2(FreeImage_GetWidth(m_texture) - 1, FreeImage_GetHeight(m_texture) - 1);
+    pitch = FreeImage_GetPitch(m_texture);
+    bits = ((BYTE *)FreeImage_GetBits(m_texture)) + (static_cast<unsigned int>(tex_coord.y) * pitch);
+    pixel = (FIRGBF *)bits;
+    return vec3(pixel[static_cast<unsigned int>(tex_coord.x)].red, pixel[static_cast<unsigned int>(tex_coord.x)].green, pixel[static_cast<unsigned int>(tex_coord.x)].blue);
+  }
+}