X-Git-Url: http://git.localhorst.tv/?a=blobdiff_plain;f=src%2Fgeometry.cpp;h=cd28bab4453836489e20531cb60ad39223ca4f94;hb=4485397da18a25dfd1a51e864814887b66ba0f2e;hp=df48ad3deac2c440f66d89f8fb69e69aac1e9b88;hpb=8881c507009521d08648560984c0f50166224542;p=blank.git

diff --git a/src/geometry.cpp b/src/geometry.cpp
index df48ad3..cd28bab 100644
--- a/src/geometry.cpp
+++ b/src/geometry.cpp
@@ -13,117 +13,94 @@ bool Intersection(
 	glm::vec3 *normal
 ) {
 	float t_min = 0.0f;
-	float t_max = 1.0e5f;
+	float t_max = std::numeric_limits<float>::infinity();
 	const glm::vec3 aabb_pos(M[3].x, M[3].y, M[3].z);
 	const glm::vec3 delta = aabb_pos - ray.orig;
 
 	glm::vec3 t1(t_min, t_min, t_min), t2(t_max, t_max, t_max);
-	bool x_swap = false, y_swap = false, z_swap = false;
 
-	{ // X
-		const glm::vec3 xaxis(M[0].x, M[0].y, M[0].z);
-		const float e = glm::dot(xaxis, delta);
-		const float f = glm::dot(ray.dir, xaxis);
+	for (int i = 0; i < 3; ++i) {
+		const glm::vec3 axis(M[i].x, M[i].y, M[i].z);
+		const float e = glm::dot(axis, delta);
+		const float f = glm::dot(axis, ray.dir);
 
 		if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
-			t1.x = (e + aabb.min.x) / f;
-			t2.x = (e + aabb.max.x) / f;
+			t1[i] = (e + aabb.min[i]) / f;
+			t2[i] = (e + aabb.max[i]) / f;
 
-			if (t1.x > t2.x) {
-				std::swap(t1.x, t2.x);
-				x_swap = true;
-			}
-			if (t1.x > t_min) {
-				t_min = t1.x;
-			}
-			if (t2.x < t_max) {
-				t_max = t2.x;
-			}
-			if (t_max < t_min) {
-				return false;
-			}
-		} else {
-			if (aabb.min.x - e > 0.0f || aabb.max.x < 0.0f) {
-				return false;
-			}
-		}
-	}
-
-	{ // Y
-		const glm::vec3 yaxis(M[1].x, M[1].y, M[1].z);
-		const float e = glm::dot(yaxis, delta);
-		const float f = glm::dot(ray.dir, yaxis);
+			t_min = std::max(t_min, std::min(t1[i], t2[i]));
+			t_max = std::min(t_max, std::max(t1[i], t2[i]));
 
-		if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
-			t1.y = (e + aabb.min.y) / f;
-			t2.y = (e + aabb.max.y) / f;
-
-			if (t1.y > t2.y) {
-				std::swap(t1.y, t2.y);
-				y_swap = true;
-			}
-			if (t1.y > t_min) {
-				t_min = t1.y;
-			}
-			if (t2.y < t_max) {
-				t_max = t2.y;
-			}
 			if (t_max < t_min) {
 				return false;
 			}
 		} else {
-			if (aabb.min.y - e > 0.0f || aabb.max.y < 0.0f) {
+			if (aabb.min[i] - e < 0.0f || -aabb.max[i] - e > 0.0f) {
 				return false;
 			}
 		}
 	}
 
-	{ // Z
-		const glm::vec3 zaxis(M[2].x, M[2].y, M[2].z);
-		const float e = glm::dot(zaxis, delta);
-		const float f = glm::dot(ray.dir, zaxis);
-
-		if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
-			t1.z = (e + aabb.min.z) / f;
-			t2.z = (e + aabb.max.z) / f;
-
-			if (t1.z > t2.z) {
-				std::swap(t1.z, t2.z);
-				z_swap = true;
-			}
-			if (t1.z > t_min) {
-				t_min = t1.z;
-			}
-			if (t2.z < t_max) {
-				t_max = t2.z;
-			}
-			if (t_max < t_min) {
-				return false;
-			}
-		} else {
-			if (aabb.min.z - e > 0.0f || aabb.max.z < 0.0f) {
-				return false;
-			}
-		}
-	}
+	glm::vec3 min_all(min(t1, t2));
 
 	if (dist) {
 		*dist = t_min;
 	}
 	if (normal) {
-		if (t1.x > t1.y) {
-			if (t1.x > t1.z) {
-				*normal = glm::vec3(x_swap ? 1 : -1, 0, 0);
+		glm::vec4 norm(0.0f);
+		if (min_all.x > min_all.y) {
+			if (min_all.x > min_all.z) {
+				norm.x = t2.x < t1.x ? 1 : -1;
 			} else {
-				*normal = glm::vec3(0, 0, z_swap ? 1 : -1);
+				norm.z = t2.z < t1.z ? 1 : -1;
 			}
-		} else if (t1.y > t1.z) {
-			*normal = glm::vec3(0, y_swap ? 1 : -1, 0);
+		} else if (min_all.y > min_all.z) {
+			norm.y = t2.y < t1.y ? 1 : -1;
 		} else {
-			*normal = glm::vec3(0, 0, z_swap ? 1 : -1);
+			norm.z = t2.z < t1.z ? 1 : -1;
 		}
+		norm = M * norm;
+		*normal = glm::vec3(norm);
 	}
 	return true;
 }
 
+bool CullTest(const AABB &box, const glm::mat4 &MVP) {
+	// transform corners into clip space
+	glm::vec4 corners[8] = {
+		{ box.min.x, box.min.y, box.min.z, 1.0f },
+		{ box.min.x, box.min.y, box.max.z, 1.0f },
+		{ box.min.x, box.max.y, box.min.z, 1.0f },
+		{ box.min.x, box.max.y, box.max.z, 1.0f },
+		{ box.max.x, box.min.y, box.min.z, 1.0f },
+		{ box.max.x, box.min.y, box.max.z, 1.0f },
+		{ box.max.x, box.max.y, box.min.z, 1.0f },
+		{ box.max.x, box.max.y, box.max.z, 1.0f },
+	};
+	for (glm::vec4 &corner : corners) {
+		corner = MVP * corner;
+		corner /= corner.w;
+	}
+
+	int hits[6] = { 0, 0, 0, 0, 0, 0 };
+
+	// check how many corners lie outside
+	for (const glm::vec4 &corner : corners) {
+		if (corner.x >  1.0f) ++hits[0];
+		if (corner.x < -1.0f) ++hits[1];
+		if (corner.y >  1.0f) ++hits[2];
+		if (corner.y < -1.0f) ++hits[3];
+		if (corner.z >  1.0f) ++hits[4];
+		if (corner.z < -1.0f) ++hits[5];
+	}
+
+	// if all corners are outside any given clip plane, the test is true
+	for (int hit : hits) {
+		if (hit == 8) return true;
+	}
+
+	// otherwise the box might still get culled completely, but can't say for sure ;)
+	return false;
+}
+
 }