Still buggy but somewhat workable FPS control.

src/render_utils.c

@@ -11,16 +11,34 @@ inline void CameraState_Init(CameraState* camera_state) {
   };
   // clang-format on
 
+  camera_state->forward[0] = 0.f;
+  camera_state->forward[1] = 0.f;
+  camera_state->forward[2] = -1.f;
+
+  camera_state->right[0] = 1.f;
+  camera_state->right[1] = 0.f;
+  camera_state->right[2] = 0.f;
+
+  camera_state->up[0] = 0.f;
+  camera_state->up[1] = 1.f;
+  camera_state->up[2] = 0.f;
+
   memcpy(&camera_state->mtxView, &mtx_identity, sizeof(camera_state->mtxView));
+  CameraState_CalcFromMatrix(camera_state, &camera_state->mtxView);
 }
 
 void CameraState_CalcFromMatrix(CameraState* camera_state, simd4x4f* mtx) {
-  float right[3] = {mtx->x[0], mtx->y[0], mtx->z[0]};
-  float up[3] = {mtx->x[1], mtx->y[1], mtx->z[1]};
-  float forward[3] = {-mtx->x[2], -mtx->y[2], -mtx->z[2]};
 
-  camera_state->heading = atan2(forward[2], -forward[0]);
+  camera_state->forward[0] = mtx->x[2];
-  camera_state->pitch = asin(-forward[1]);
+  camera_state->forward[1] = mtx->y[2];
+  camera_state->forward[2] = mtx->z[2];
+
+  camera_state->right[0] = mtx->x[0];
+  camera_state->right[1] = mtx->y[0];
+  camera_state->right[2] = mtx->z[0];
+
+  camera_state->heading = atan2(-camera_state->forward[2], camera_state->forward[0]);
+  camera_state->pitch = asin(camera_state->forward[1]);
 
   simd4x4f rot_mat = *mtx;
   rot_mat.w = simd4f_create(0.f, 0.f, 0.f, 1.f);
@@ -33,7 +51,6 @@ void CameraState_CalcFromMatrix(CameraState* camera_state, simd4x4f* mtx) {
   camera_state->pos[1] = -simd4f_get_y(eye);
   camera_state->pos[2] = -simd4f_get_z(eye);
 
-
 //  gLog ("ViewMat");
 //  gLog ("%f, %f, %f, %f", mtx->x[0], mtx->x[1], mtx->x[2], mtx->x[3]);
 //  gLog ("%f, %f, %f, %f", mtx->y[0], mtx->y[1], mtx->y[2], mtx->y[3]);
@@ -55,6 +72,14 @@ void CameraState_CalcToMatrix(CameraState* camera_state, simd4x4f* mtx) {
   simd4f up = simd4f_cross3(right, forward);
   simd4f center = simd4f_add(simd4f_mul(forward, simd4f_splat(d)), eye);
 
+  camera_state->forward[0] = -simd4f_get_x(forward);
+  camera_state->forward[1] = -simd4f_get_y(forward);
+  camera_state->forward[2] = -simd4f_get_z(forward);
+
+  camera_state->right[0] = simd4f_get_x(right);
+  camera_state->right[1] = simd4f_get_y(right);
+  camera_state->right[2] = simd4f_get_z(right);
+
   simd4x4f_lookat(mtx, eye, center, up);
 }
 
@@ -64,25 +89,25 @@ inline void CameraState_Update(
     float mouse_dx,
     float mouse_dy,
     float accel[3]) {
-  CameraState_CalcFromMatrix(camera_state, &camera_state->mtxView);
+  const float mouse_sensitivity = 15.0f;
 
-  camera_state->heading += dt * mouse_dx * M_PI / 180.f;
+  camera_state->heading -= dt * mouse_dx * mouse_sensitivity * M_PI / 180.f;
   if (camera_state->heading < -M_PI) {
     camera_state->heading += M_PI;
   } else if (camera_state->heading > M_PI) {
     camera_state->heading -= M_PI;
   }
-  camera_state->heading = dt * mouse_dy * M_PI / 180.f;
+  camera_state->pitch += dt * mouse_dy * mouse_sensitivity * M_PI / 180.f;
-  if (camera_state->heading < -M_PI * 0.49) {
+  if (camera_state->pitch < -M_PI * 0.49) {
-    camera_state->heading = -M_PI * 0.49;
+    camera_state->pitch = -M_PI * 0.49;
-  } else if (camera_state->heading > M_PI * 0.49) {
+  } else if (camera_state->pitch > M_PI * 0.49) {
-    camera_state->heading = M_PI * 0.49;
+    camera_state->pitch = M_PI * 0.49;
   }
 
   for (int i = 0; i < 3; i++) {
-    camera_state->vel[i] += dt * accel[i];
+    camera_state->vel[i] += dt * accel[0] * camera_state->forward[i] + dt * accel[2] * camera_state->right[i] + dt * accel[1] * camera_state->up[i];
     camera_state->pos[i] += dt * camera_state->vel[i];
-    camera_state->vel[i] = camera_state->vel[i] * 0.5;
+    camera_state->vel[i] = camera_state->vel[i] * 0.1;
   }
 
   CameraState_CalcToMatrix(camera_state, &camera_state->mtxView);

src/render_utils.h

@@ -17,6 +17,9 @@ typedef struct {
   float pitch;
   float vel[3];
   float pos[3];
+  float forward[3];
+  float right[3];
+  float up[3];
 } CameraState;
 
 void CameraState_Init(CameraState* camera_state);

src/vissim.cc

@@ -61,6 +61,9 @@ enum ViewMode { ViewModeSimulation = 0, ViewModeGuizmoTest = 1 };
 ViewMode gViewMode = ViewModeSimulation;
 bool gGizmoEnabled = true;
 
+enum ControlMode { ControlModeNone = 0, ControlModeFirstPersonView = 1 };
+ControlMode gControlMode = ControlModeNone;
+
 using namespace std;
 
 static void error_callback(int error, const char* description) {
@@ -519,7 +522,7 @@ int main(void) {
   simulator_init();
 
   simd4x4f_translation(&gCameraState->mtxView, 0.1f, 0.1f, -0.5f);
-  simd4f eye = simd4f_create(0.f, 3.f, 10.f, 1.f);
+  simd4f eye = simd4f_create(0.f, 0.f, 10.f, 1.f);
 
   simd4x4f_lookat(
       &gCameraState->mtxView,
@@ -580,34 +583,56 @@ int main(void) {
       float menu_bar_height = ImGui::GetWindowHeight();
       ImGui::EndMainMenuBar();
 
-      CameraState_CalcFromMatrix(gCameraState, &gCameraState->mtxView);
+      if (glfwGetMouseButton(gWindow, GLFW_MOUSE_BUTTON_RIGHT)) {
+        if (gControlMode == ControlModeNone) {
+          gControlMode = ControlModeFirstPersonView;
+          CameraState_CalcFromMatrix(gCameraState, &gCameraState->mtxView);
+          glfwSetInputMode(gWindow, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
+        }
+      } else {
+        gControlMode = ControlModeNone;
+        glfwSetInputMode(gWindow, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
+      }
 
-      ImGui::Begin("HeadingPitch");
+      if (gControlMode == ControlModeFirstPersonView) {
+        float camera_accel[3] = {0.f, 0.f, 0.f};
+
+        if (glfwGetKey(gWindow, GLFW_KEY_W)) {
+          camera_accel[0] -= 100.f;
+        }
+        if (glfwGetKey(gWindow, GLFW_KEY_S)) {
+          camera_accel[0] += 100.f;
+        }
+        if (glfwGetKey(gWindow, GLFW_KEY_C)) {
+          camera_accel[1] -= 100.f;
+        }
+        if (glfwGetKey(gWindow, GLFW_KEY_SPACE)) {
+          camera_accel[1] += 100.f;
+        }
+        if (glfwGetKey(gWindow, GLFW_KEY_A)) {
+          camera_accel[2] -= 100.f;
+        }
+        if (glfwGetKey(gWindow, GLFW_KEY_D)) {
+          camera_accel[2] += 100.f;
+        }
+
+        CameraState_Update(gCameraState, frame_delta_time, gGuiInputState->mousedX, gGuiInputState->mousedY, camera_accel);
+      }
+
+      ImGui::Begin("Camera Controls");
 
       bool changed = false;
       changed = ImGui::SliderFloat("Heading", &gCameraState->heading, -M_PI * 0.98, M_PI * 0.98);
-      changed = changed || ImGui::SliderFloat("Pitch", &gCameraState->pitch, -M_PI * 0.49, M_PI * 0.49);
+      changed = ImGui::SliderFloat("Pitch", &gCameraState->pitch, -M_PI * 0.49, M_PI * 0.49) || changed;
 
-      float camera_accel[3] = {0.f, 0.f, 0.f};
+      changed = ImGui::SliderFloat3("Forward", gCameraState->forward, -1.f, 1.f) || changed;
-      if (glfwGetKey(gWindow, GLFW_KEY_W)) {
+      changed = ImGui::SliderFloat3("Right", gCameraState->right, -1.f, 1.f) || changed;
-        camera_accel[0] -= 100.f;
+      changed = ImGui::SliderFloat3("Up", gCameraState->up, -1.f, 1.f) || changed;
-      }
+      changed = ImGui::SliderFloat3("Pos", gCameraState->pos, -100.f, 100.f) || changed;
-      if (glfwGetKey(gWindow, GLFW_KEY_S)) {
-        camera_accel[0] += 100.f;
-      }
-      if (glfwGetKey(gWindow, GLFW_KEY_A)) {
-        camera_accel[2] += 100.f;
-      }
-      if (glfwGetKey(gWindow, GLFW_KEY_D)) {
-        camera_accel[2] -= 100.f;
-      }
 
       if (changed) {
         CameraState_CalcToMatrix(gCameraState, &gCameraState->mtxView);
-      } else {
-        CameraState_Update(gCameraState, frame_delta_time, 0.f, 0.f, camera_accel);
       }
-
       ImGui::End();
 
       if (show_demo_window) ImGui::ShowDemoWindow();