initial commit-moved from vulkan_guide

src/scene/camera.cpp

@@ -0,0 +1,83 @@
+#include "camera.h"
+#include <glm/gtx/transform.hpp>
+#include <glm/gtx/quaternion.hpp>
+#include <SDL2/SDL.h>
+#include <algorithm>
+#include <cmath>
+
+void Camera::update()
+{
+    glm::mat4 cameraRotation = getRotationMatrix();
+    position += glm::vec3(cameraRotation * glm::vec4(velocity * moveSpeed, 0.f));
+}
+
+void Camera::processSDLEvent(SDL_Event& e)
+{
+    if (e.type == SDL_KEYDOWN) {
+        // Camera uses -Z forward convention (right-handed)
+        if (e.key.keysym.sym == SDLK_w) { velocity.z = -1; }
+        if (e.key.keysym.sym == SDLK_s) { velocity.z = 1; }
+        if (e.key.keysym.sym == SDLK_a) { velocity.x = -1; }
+        if (e.key.keysym.sym == SDLK_d) { velocity.x = 1; }
+    }
+
+    if (e.type == SDL_KEYUP) {
+        if (e.key.keysym.sym == SDLK_w) { velocity.z = 0; }
+        if (e.key.keysym.sym == SDLK_s) { velocity.z = 0; }
+        if (e.key.keysym.sym == SDLK_a) { velocity.x = 0; }
+        if (e.key.keysym.sym == SDLK_d) { velocity.x = 0; }
+    }
+
+    if (e.type == SDL_MOUSEBUTTONDOWN && e.button.button == SDL_BUTTON_RIGHT) {
+        rmbDown = true;
+        SDL_SetRelativeMouseMode(SDL_TRUE);
+    }
+    if (e.type == SDL_MOUSEBUTTONUP && e.button.button == SDL_BUTTON_RIGHT) {
+        rmbDown = false;
+        SDL_SetRelativeMouseMode(SDL_FALSE);
+    }
+
+    if (e.type == SDL_MOUSEMOTION && rmbDown) {
+        // Mouse right (xrel > 0) turns view right with -Z-forward
+        yaw += (float)e.motion.xrel * lookSensitivity;   // axis = +Y
+        // Mouse up (yrel < 0) looks up with -Z-forward
+        pitch -= (float)e.motion.yrel * lookSensitivity;
+    }
+
+    if (e.type == SDL_MOUSEWHEEL) {
+        // Ctrl modifies FOV, otherwise adjust move speed
+        const bool ctrl = (SDL_GetModState() & KMOD_CTRL) != 0;
+        const int steps = e.wheel.y; // positive = wheel up
+        if (ctrl) {
+            // Wheel up -> zoom in (smaller FOV)
+            fovDegrees -= steps * 2.0f;
+            fovDegrees = std::clamp(fovDegrees, 30.0f, 110.0f);
+        } else {
+            // Exponential scale for pleasant feel
+            float factor = std::pow(1.15f, (float)steps);
+            moveSpeed = std::clamp(moveSpeed * factor, 0.001f, 5.0f);
+        }
+    }
+}
+
+glm::mat4 Camera::getViewMatrix()
+{
+    // to create a correct model view, we need to move the world in opposite
+    // direction to the camera
+    //  so we will create the camera model matrix and invert
+    glm::mat4 cameraTranslation = glm::translate(glm::mat4(1.f), position);
+    glm::mat4 cameraRotation = getRotationMatrix();
+    return glm::inverse(cameraTranslation * cameraRotation);
+}
+
+glm::mat4 Camera::getRotationMatrix()
+{
+    // fairly typical FPS style camera. we join the pitch and yaw rotations into
+    // the final rotation matrix
+
+    glm::quat pitchRotation = glm::angleAxis(pitch, glm::vec3 { 1.f, 0.f, 0.f });
+    // Yaw around +Y keeps mouse-right -> turn-right with -Z-forward
+    glm::quat yawRotation = glm::angleAxis(yaw, glm::vec3 { 0.f, 1.f, 0.f });
+
+    return glm::toMat4(yawRotation) * glm::toMat4(pitchRotation);
+}